The 41-year-old signed off after a 24-year career with an epic 2-hour, 12-minute three-set defeat to Team World's Jack Sock and Frances Tiafoe.
It seemed the scriptwriters had set it up perfectly, with Federer serving on match point in a match tiebreak. But the Americans Sock and Tiafoe saved the point before going on to win 4–6 7–6 –.
The Swiss was raucously cheered onto court – and then off court – by a packed O2 Arena in the British capital.
"It's been a wonderful day. I told the guys I'm happy, I'm not sad. It feels great to be here," Federer said after his last match, his voice cracking with emotion. "I enjoyed tying my shoes one more time, and everything was the last time. With all the matches and having the guys being here, fans family, friends, I didn't feel the stress so much.
"I'm so happy I made it through. The match was great, I couldn't be happier. It's been wonderful."
READ MORE: Laver Cup 2022 preview
Re-live the match as it happened below.
All times below are British Summer Time (UTC/GMT +1 hour). Most recent updates first.
12:44am - Full house hanging around for Federer
"Love you all, it's been an amazing journey" are Federer's final words to the crowd.
And with that, the crowd erupts into another chant of "Roger, Roger". It's still a full house, nearing 1am.
As music artiste Ellie Goulding takes to the stage to perform, that's where we'll leave our coverage this evening.
Thank you, Roger Federer.
12:41am - Emotional Federer thanks wife
"It's been a perfect journey" since the start, Federer says. "I would do it all over again."
The still-full O2 Arena cheers the Swiss one more time. "Thank you everybody, I've had so many people cheer me on. You guys here tonight. It means the world."
Federer is asked about his family and jokes through tears: "we have to go there?"
Mirka, his wife, is also in tears court-side. "My wife's been so supportive," Federer says before struggling to compose himself. "She could have stopped me a long, long time ago but she didn't. She kept me going and allowed me to play, it's amazing. Thank you."
He also thanks his parents, who are watching on in the crowd.
12:38am - Federer: "I'm happy, not sad"
We're about to hear from the Swiss legend.
"It's been a wonderful day. I told the guys I'm happy, I'm not sad. It feels great to be here," Federer says, his voice cracking with emotion. "I enjoyed tying my shoes one more time, and everything was the last time. With all the matches and having the guys being here, fans family, friends, I didn't feel the stress so much, even though I did think something was going to go!
"I'm so happy I made it through. The match was great, I couldn't be happier. It's been wonderful. Of course, playing with Rafa on the same team, having the guys – everybody – here, all the legends. Rocket (Rod Laver), Edberg – Stefan, thank you.
"I didn't want to feel lonely out there. It felt lonely out there for a second when they wanted me to come out one more time. To say goodbye as a team, I was always a team player at heart… singles doesn't really do that a whole lot, but I had a team that travelled with me around the world so thanks to them."
Federer then names all his Team Europe teammates. "It's been a pleasure playing all these Laver Cups and it does feel like a celebration to me. I wanted to feel like this at the end and it's exactly what I hoped for."
12:31am - Federer tribute
There are tears aplenty – from Federer, Nadal, Stefanos Tsitsipas, and many in the crowd.
"Roger, Roger," the crowd begins chanting as a video celebrating Federer's career plays in the arena.
"He has served as such a big inspiration to me and to so many other players," Djokovic says in the video.
12:28am - Federer takes centre stage
Still no-one has left the arena. The crowd give Federer one final standing ovation of his career as the tears flow.
Team World might have won that match, and levelled the Laver Cup at 2–2, but that's not the story tonight.
All eyes are on one man. Nadal, too, looks emotional on the Europe bench.
12:25am - Team World ensure no fairytale ending for Federer
Nadal somehow ducks out of the way of a huge hit from Tiafoe that nearly takes him out. 10-9 World, and the Americans bring up match point.
A fantastic forehand winner down the line from Jack Sock! Team World win it!
All four embrace at the net. Roger Federer's career comes to an end in an epic. "It's all good," Federer says.
World win, 4–6 7–6 –
Federer is now being hugged, to a man, by everyone on Team Europe as the emotions hit. Now he goes over to the World bench, with everyone also thanking him for his career.
Match tiebreak: 9-9
Sock is called for a centre-line fault. He challenges and it's ruled to still be a fault. Federer slices a shot into the net. 7-6 World.
Federer with an amazing shot to contain Sock and Tiafoe. It's kicked this crowd back into life. 7-7, and anyone's game.
Tiafoe hits one right into Federer's upper arm. The crowd jeers. 8-7 World.
The American can't deal with the speed of a Nadal return on his own serve and what do you know, it's 8-8. Whoever wins this next point will have match point.
It's Europe who bring up match point, and the crowd is deafening. Tiafoe finds the net. 9-8 Europe.
Look at who's serving on match point. Roger Federer.
"Let's go, Roger, let's go" starts up again.
Nearly an ace! But it's called a fault. The match point is saved as Tiafoe does amazingly at the net to intercept and force Federer into the error. 9-9.
Match tiebreak: 6-6
No-one has left, despite it now being Saturday morning in London.
World win an incredible point as Sock somehow gets his racket to a ball that was almost dead. Hands on heads on the Europe bench. 4-3 World.
A fantastic rally follows, and with Federer out of position with both Europeans at the net, Tiafoe can't get the ball over. 4-4.
The birthday boy Sock is doing all sorts here. He slips on the court but somehow plays the ball. 5-4 World.
With all four players at the net, playing soft lobs at each other, Nadal finds the space for a backhand slice that beats both Americans. 5-5.
An ace from Roger Federer! 6-5 Europe. The crowd bursts into raptures. The entire European bench is on their feet.
Now one long from the Europeans and we're level again. 6-6.
Match tiebreak: 3-3
Team World finally get into this as Federer lobs a return from a Sock serve into the net. 3-1 Europe.
Now another Europe shot long and Sock has gotten World back in this. 3-2 Europe.
Nadal on serve – dealt with well by the Americans, and Federer just sticks his racket up but the shot is long. 3-3.
Match tiebreak: Europe 3-0
This crowd is still alive, loud and cheering.
Match tiebreak time – Tiafoe will serve first. And Europe draw first blood with a long return from Sock, unable to deal with a Nadal shot. 1-0 Europe.
Federer serves next. Nadal is back in this! Tiafoe can't get enough power on his shot and Nadal smashes a return easily. 2-0 Europe.
The crowd is cheering every European point. It's a partisan one. And understandably so. Federer and Nadal have a three-point lead.
12:05am - World force match tiebreak (4–6 7–6)
Now Federer's turn to send one long. Team World now have breathing room. 5-2 World.
Remember if Team World win this tiebreak, we play another (match) tiebreak to 10. Now World bring up four set points. 6-2 World.
Europe can't get a hold and Team World have levelled to force the match tiebreak.
It's Jack Sock's birthday now that we're past midnight!
Second-set tiebreak: World 4-2
The crowd aren't happy with chair ump Mohamed Lahyani calling a let on Federer's first serve. Tiafoe returns the second serve brilliantly. 1-0 World.
Nadal still can't deal with shots at his body as he awkwardly puts the ball back into the net. 2-0 World.
Europe get on the board as the clock hits midnight, Tiafoe going long. 2-1 World.
A late fault call on Nadal's serve, and a late challenge from the Spaniard. It was indeed out. His second serve is more conservative, Sock returns it well and Nadal completely misjudges his return. 3-1 World.
Tiafoe can't handle a quick sequence of volleys on the next point and Europe just about keep up. 3-2 World.
Nadal is struggling with his points here. At the changeover in the tiebreak, World leads 4-2, the Spaniard having sent one long.
11:58pm - Second-set tiebreak (6–6)
A forehand winner down the line from Roger Federer on Sock's serve brings it to 15–15 before the Americans edge back ahead.
"Great serve!" comes the yell from the benches.
Tiafoe plays one into the net from a Federer return. Djokovic raises an arm in celebration on the Europe bench.
It's Nadal's turn to misplay as he sends one well wide. But Tiafoe makes another unforced error! We're back to deuce.
Finally a let cord goes Tiafoe's way as World take the advantage with the ball just about making it over the net. And Federer returns into the net.
We're headed to a second-set tiebreak, first to seven. If the Americans win it, we will head to a first-to-ten match tiebreak.
Fed/Nad 6–4 6–5* Soc/Tia
Tiafoe is running all over the court, as is Nadal – but it's the American who gets the upper hand.
World go ahead 0-30 on Nadal's serve, and the Spaniard then sees an unlucky return hit the top of the net and go wide.
Three break points for World. The first is saved as Sock finds the net. The second is also saved; Tiafoe plays a smart return but it's just wide.
And the third is saved too! A looping return from Sock goes long. Deuce.
Tiafoe plays one wide, yells at himself in frustration, and challenges the call – incorrectly. Advantage Europe, but Sock keeps the set alive sending one out of Federer's reach.
Now a double fault from Nadal brings up a fourth break point for World! The crowd kick back into life to cheer on the Europeans, but it's advantage World – and a pair of brilliant Federer smashes saves that break point too.
Nadal's next serve is brilliantly returned by Tiafoe, and Fedal can only stare at each other. Federer seems to think he heard a let call. No matter – the fifth break point comes and goes.
An incredible rally between Nadal and Tiafoe for the next point, and when Federer finally gets involved, Sock slices one out of reach. John McEnroe, the World captain, is up on his feet cheering. Somehow, the Americans can't convert on their sixth break point. This game has now gone on over 10 minutes. We're approaching midnight in London.
Europe get advantage as Tiafoe lobs one high and into the stands at the O2 Arena. And Sock finds the net for a European hold. What a game.
Fed/Nad 6–4 *5–5 Soc/Tia
Team World go 30-0 up in this crucial game before Tiafoe double-faults to bring Europe back into it.
Sock then finds the net, slamming his racket into the court in frustration. 30–30 and Europe are two points away from winning Roger Federer's farewell.
A shot goes wide for Fedal, and the pair can't believe it. They then can't deal with Sock's height as the American smashes one out of Nadal's reach.
Fed/Nad 6–4 5–4* Soc/Tia
Team World hold fairly easily to keep the second set equal.
In the following game, Tiafoe is almost superhuman as he keeps a point alive for World, but and Fedal seem to have the game under control before Nadal can't deal with one right at him and returns into the net.
The crowd cheer on the Europeans, who eke out advantage, before closing out the game.
"Great serving, Rog," say the bench. Tiafoe will have to serve to stay in the match.
"For me it's difficult to read how the ball is coming, especially his forehand," Nadal says of Sock.
Fed/Nad 6–4 4–3* Soc/Tia
Federer and Nadal hold serve – so they've won three games in a row.
"I don't know what happened," Federer says of the double hit. "I thought he hit the ball then hit the floor," Nadal responds.
Fed/Nad 6–4 *3–3 Soc/Tia
Tiafoe double-faults and Fedal bring up two break points.
Can they get back level in this set?
Nearly an ace in response but it's just wide.
Then the umpire calls Tiafoe's racket hitting the ball twice – that's a break!
Fed/Nad 6–4 2–3* Soc/Tia
What a point to start the next game!
Nadal nearly gets one around the net – and Tiafoe runs across court to give him a low-five. Novak Djokovic is smiling on the bench.
Team Europe hang on as Tiafoe, from close in, puts one into the net.
Fed/Nad 6–4 *1–3 Soc/Tia
And now the Americans find their serve under challenge.
Nadal does well to win the opening point of this game before Jack Sock can't control a return on the second and sends it long.
Two break points come up. Can Fedal break back immediately? Not on the first with a shot that's wide.
And the next shot from Federer is wide too! The crowd momentarily goes silent. Deuce.
Unforced error from Sock! His return down the line is long. Then Federer completely misplays his return to Sock's second serve on break point.
Back at deuce. A lovely backhand slice from Tiafoe gives the Americans the advantage – can they hold serve? Yes they can.
Fed/Nad 6–4 1–2* Soc/Tia
Fedal are on the ropes in this game.
More unforced errors leaves Federer and Nadal reeling at 0–40, facing three break points.
Nadal saves the first of the three break points as Tiafoe misreads the shot and goes the wrong way on court.
An ace appears to have saved the second but Tiafoe challenges. HawkEye says it clipped the centre line – so Team World lose a challenge.
But on the third break point, Federer plays the wrong shot and the Americans break.
Fed/Nad 6–4 *1–1 Soc/Tia
Great reactions from Nadal to keep a rally alive after a couple of smashes from Sock, then an unforced error from Tiafoe means Fedal edge ahead in this next game at 15–30.
The tall Sock is proving a handful on smashes. Tiafoe then serves an ace – he's had a few already – and a second to level the set.
Fed/Nad 6–4 1–0* Soc/Tia
The "let's go Roger let's go" chant starts up again.
Fedal, on serve to start this second set, are off to a quick start.
However Nadal has to react quickly to duck out of the way of a howitzer of a return from Tiafoe that goes out. All smiles from everyone.
Fed/Nad *6–4 Soc/Tia
Nadal has no real answer to Frances Tiafoe's serves.
However, the Spaniard does finally get a return in and wins a point with a great cross-court shot (below).
Sock then can't deal with a Federer return on the next point and what do you know, we're on deuce.
Advantage Europe! Fedal bring up a break point – and set point – as Federer plays a smart slice.
Then Sock can only clip the top of the net on the next rally and Fedal take the set!
Fed/Nad 5–4* Soc/Tia
A fantastic parallel return from Sock down the line behind Federer's back.
The next quick rally ends with Nadal finding the net. For the first time this match, the serve is under pressure.
Fedal save the break to force deuce. Tiafoe returns Nadal's serve into the net, then Federer playing at the net slices one out of the reach of the Americans.
We're still on serve.
10:45pm - Everyone's watching this
Fed/Nad *4–4 Soc/Tia
The Americans are enjoying this as much as Fedal are.
Sock and Tiafoe are keeping their end of the bargain up, holding serve once more.
Fed/Nad 4–3* Soc/Tia
Aside from Sock, both Federer and Nadal are Olympic champions in doubles too.
Federer won gold at Beijing 2008 alongside Stan Wawrinka; Nadal at Rio 2016 alongside Marc López.
Fedal keep this match on serve.
Fed/Nad *3–3 Soc/Tia
A Fedal return is long and Tiafoe challenges immediately as it is not called out.
Good challenge, and that's the sixth game. "Let's go, Roger, let's go" is the chant from the crowd.
Fed/Nad 3–2* Soc/Tia
A fantastic volley – quick reflexes – from Federer to bring up 40–15 on the point.
The next rally is competitive but a return from Sock is long.
All on serve so far.
Fed/Nad *2–2 Soc/Tia
Team World control the next game, with both Federer and Nadal finding the net on returns from close in.
Fedal back on serve.
Fed/Nad 2–1* Soc/Tia
A Federer return goes through a hole in the net.
World captain John McEnroe jumps off the bench to argue the call. No dice. The next point goes to Sock and Tiafoe.
But it's a side note as "Fedal" take the game.
Fed/Nad *1–1 Soc/Tia
The Americans level the set.
"Roger Federer to serve," intones chair ump Mohamed Lahyani of Sweden.
That gets a huge cheer.
Fed/Nad 1–0* Soc/Tia
Tiafoe cannot deal with Nadal's serves, and Federer has gotten off to a strong start too.
The Swiss played a lovely little slice to win a point in that opening game.
Sock/Tiafoe serve next.
10:12pm - Underway
Nadal gets us underway with a serve into the net before an ace on his second serve. Frances Tiafoe challenges the in call immediately – and he's right.
That's a double fault.
10:07pm - Sock a tough challenge
Jack Sock is of course a doubles specialist.
He's a former world number 2 and won Olympic gold and bronze in mixed doubles and men's doubles at Rio 2016 for Team USA.
Not an easy opponent for Federer and Nadal.
10:03pm - Standing ovation
The crowd are on their feet, to a man and woman and child.
Every single person in the arena just cheered Federer and Nadal onto court.
10:01pm - Federer ready
Federer hugs each of his Team Europe teammates in the locker-room.
The Swiss maestro is ready for his final farewell.
9:48pm - De Minaur gets World on the board
After a long 2 hours 28 minutes, Team World has its first point on the board.
Alex De Minaur converts on his first match point in the tiebreak to win 5–7 6–3 –.
Up next, Roger.
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It was at the Olympic Games Sydney 2000, Roger Federer's first Olympics, where his life would change forever.
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9:29pm - Match tiebreak incoming
De Minaur opens up a small lead in this game, then converts on his third set point against serve to square this match at one set all.
We're headed to a match tiebreak.
9:26pm - Slow court
It's not unfair to suggest this court is playing slow for an indoor hard surface.
We're 2 hours 6 minutes into this match. De Minaur leads the second 5–3.
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Three hundred and ten weeks at world number one, including 237 consecutively.
Numbers from an incredible career which you can read more about: Federer's career and records by numbers
8:42pm - Murray takes first set
Murray finally converts on a set point as De Minaur double-faults, and after what feels like an eternity, the 12th game – and first set – go the way of Team Europe 7–5.
8:37pm - Grinding opening set still going
Murray and De Minaur are still in the first set after nearly 80 minutes of play.
This 12th game alone has taken over 10 minutes, with multiple deuces. The crowd will have to wait a bit longer to see Roger.
What will Roger Federer do in retirement?
What's next for Federer after today?
Earlier this week he discussed with the BBC about why he finally had to call it a day, and his future plans.
Unsurprisingly, he wants to stay involved in tennis somehow.
READ MORE: Federer's post-retirement plans
7:57pm - Murray takes the lead
In the evening's opening match, Murray has come back from a break down to lead 4–3.
Remember, Federer and Nadal take on Sock and Tiafoe after this match. All matches are best-of-three, with third sets being played as a match tiebreak.
What is Federer's "perfect match"?
We hinted at it earlier below, but which of Federer's many matches does he consider the "perfect match" he played?
You have to go back all the way to 2004 for that.
7:12pm - Introductions
The two teams are introduced in the O2 Arena again for the evening session, with the loudest cheers reserved for Cam Norrie, Andy Murray, Novak Djokovic, Rafa Nadal, and Federer.
7:00pm - Murray vs De Minaur to start
Before Federer and Nadal take to the court, the British home crowd will get to cheer on Andy Murray.
The Scotsman takes on Australia's Alex de Minaur in the evening's first rubber shortly.
6:45pm - Federer to sign off against American pair
In probably around two hours' time, Roger Federer will be on court for the final professional match of his career.
Alongside Nadal, Federer will face off against Team World's American duo Jack Sock and Frances Tiafoe to conclude Day 1 of the Laver Cup.
Europe currently lead 2–0 after the afternoon session. Each match is worth one point today.
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You play many matches in a 24-year career.
But at Olympics.com, we've looked through the Swiss legend's entire repertoire and picked out five of the very best that defined his career.
Spoiler alert: it doesn't include the match that Federer himself considers to be the most "perfect" match he ever played (more on that later).
READ MORE: Five career-defining Federer matches
Reaction to Federer's retirement
Understandably, the maestro's announcement on 15 September triggered a wave of tributes from the sports world.
Nadal, for example, responded: "I wish this day would have never come. It’s a sad day for me personally and for sports around the world. It’s been a pleasure but also an honor and privilege to share all these years with you, living so many amazing moments on and off the court."
IOC President Thomas Bach added of the Beijing 2008 doubles gold medallist: "Roger Federer is a gentleman on and off the court – and a true Olympic champion. Congratulations Roger on your outstanding career, good luck for the future. Hope our paths will cross again."
READ MORE: Tributes from sports world to Federer
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Federer and Nadal are of course two men often mentioned in the discussion over who is the men's singles tennis GOAT.
Novak Djokovic, Bjorn Borg, and Rod Laver – who this very cup is named after – are also in the conversation.
Olympics.com recently took a look at the debate and tried to offer up an objective look at how the five rank up against each other.
READ MORE: Who's the men's tennis GOAT?