Spain may not be able to find a replacement to join Adri Arnaus in Tokyo after world number one tested positive for Covid for second time in two months.
It's certainly been a year of highs and lows for Jon Rahm.
The big-hitting Basque became a father in 2021 before losing out on a near-certain title triumph due to a positive Covid test, and then claiming his first major at the US Open.
But his year took another turn on Sunday (25 July) when the Spanish Olympic Committee announced that he would miss the event after testing positive again for Covid.
European Tour player Adri Arnaus was selected alongside Rahm for the men's competition at the Kasumigaseki Country Club with Rio 2016 Olympians Sergio Garcia and Rafa Cabrera Bello opting to skip Tokyo.
Garcia is focusing on making Europe's Ryder Cup team with Cabrera citing personal reasons.
Santiago Tarrio is the first alternate for Spain but time is against the national finding a replacement with the first round starting on Thursday (29 July).
'Rahmbo' denied tilt at more history
It's been a year to remember for Jon Rahm in more ways than one.
After a string of solid performances, he became a father in April with wife Kelley giving birth to son Kepa.
Days later, he was teeing it up in the Masters and finished tied for fifth at Augusta.
A fortnight after his first missed cut of the year in the Wells Fargo Championship, the 26-year-old took a share of eighth in the PGA Championship won by his friend and fellow former Arizona State University star Phil Mickelson.
That inspired 'Rahmbo' who made a superb start to the defence of his Memorial Tournament crown.
A hole-in-one helped him into a two-stroke lead after two rounds, and a third-round 64 left him six clear of the field.
But after rolling in his putt at the 18th, he was informed that he had tested positive for Covid and was forced to withdraw from the event.
Two negative tests on consecutive days cleared him to take part in the US Open, and he grabbed the opportunity with both hands.
As he moved into contention in the final round at Torrey Pines, Mickelson did his bit to make life easier for Kelley and Kepa.
The golfers met when Rahm was at college and 'Lefty' was so impressed he told his friends - and made bets - that the Spaniard would one day reach the world's top 10.
Rahm once had a reputation for hotheadedness, but showed admirable calm as he holed long putts for two closing birdies to become Spain's first US Open champion.
He dedicated his triumph to the country's golfing pioneer, five-time major winner Seve Ballesteros, who died in 2011.
The Athletic Bilbao football fanatic told Golf Channel, "I have a hard time explaining what just happened because I can't even believe I made the last two putts.
"This was definitely for Seve. I know he tried a lot and usually we think a lot about him in the Masters but I know he wanted to win this one most of all."
A disappointing opening round at Royal St George's wrecked his hopes of back-to-back majors at the Open, but four consecutive birdies on the back nine saw him take a share of third four strokes behind winner Collin Morikawa.
The pair were set to meet again in Tokyo, with Morikawa needing a win to take over as world number one.
Rahm's absence means he will remain top of the rankings regardless of what happens in Tokyo.
The event will be without the last two US Open champions after Bryson DeChambeau also tested positive for Covid.
Rio 2016 Olympian Patrick Reed will replace DeChambeau for Team USA after Patrick Cantlay and Brooks Koepka declined invitations having been next in line.
Why does Jon Rahm have a short swing?
Rahm is one of the biggest hitters on the PGA Tour despite having a shorter swing than most of his peers.
He revealed why in a press conference before the Open, hitting back at those who claimed he had "tight hips".
"I was born with a club foot on my right leg. My foot was 90 degrees turned inside and basically upside down. When I was born, they pretty much broke every bone in the ankle and I was casted within 20 minutes of being born from the knee down.
"Every week I had to go back to the hospital to get recasted so from the knee down my leg didn't grow at the same rate. So I have very limited ankle mobility on my right leg. It's a centimetre and a half shorter as well.
"I can't take a full swing because my ankle doesn't have the mobility or the stability to take it. So I learned at a very young age that I'm going to be more efficient at creating power and be consistent from a short swing."
As well as his ankle issues, Rahm has wrists which are almost inflexible outwards but hypermobile inwards enabling him to 'bow' his wrists and generate power in the downswing.
"Let your body dictate how you can swing. Simple as that." - Jon Rahm
Arnaus "pumped up" for Olympic chance
Like Rahm, Adri Arnaus played golf at college in the United States.
The Barcelona native went to Texas A&M University from 2012 to 2016 before taking the Spanish amateur title the following year.
That success persuaded him to turn pro and follow the trail blazed by Ballesteros.
He performed well on the Challenge Tour in 2018 and took victory in the season-ending Challenge Tour Grand Final, finishing second on the Order of Merit to earn a place on the 2019 European Tour.
Arnaus had three runner-up finishes in his rookie year - including at the Andalucia Masters where he was tied for second with former amateur rival Rahm - and now has seven top-fives on the full tour.
The Dubai-based 26-year-old is currently ranked 166 in the world, and was delighted to have been handed an unexpected opportunity in Tokyo to play alongside a man he knows well.
He told Gulf News, "I have played so much golf with Jon growing up so I am pumped up to be sharing this special week with him. I am just 24 days older than Jon so we have travelled the world as amateurs and more recently professionals as competitors and it will be great to be both representing Spain and be able to engage together in this unique event on the golfing calendar.
"I recall watching golf in the Olympics when I was still an amateur. I immediately made it a career target to represent Spain as a professional in the Olympics and it is hard to believe it has happened so early in my golfing career."
With Rahm out and a replacement by no means certain, it could be Arnaus flying the flag for Spain on his own in the men's tournament.