Belgium's Jasper Stuyven has won the first road cycling Monument of the 2021 season.
The 28-year-old of the Trek Segafredo team secured the biggest win of his career after breaking away from the peloton with just over 2km to go.
Stuyven held on in the final straight in via Roma to win the 299km classic in 6 hours 38:06, finishing ahead of Caleb Ewan of Australia and last year's winner Wout van Aert.
Three-time world champion Peter Sagan finished fourth, with recent Strade Bianche winner Mathieu van der Poel in fifth.
"I can’t describe how I feel. It’s unbelievable," Stuyven told organisers after the race.
"We had a plan to go for it, to try to win. I felt really good all day and the finale went well. There was a lot of fast guys in the group after the Poggio, so I knew I had to try all or nothing. And I did."
Stuyven: 'I tried to go all-in and anticipate the sprint'
The 112th edition of 'La Classicissima' - the longest race of the year - again had a thrilling finale.
The peloton remained pretty much together until the last section of the course, when a breakaway attempt was brought back with just over 24km to go.
As in the 2020 event, the race heated up on the closing Poggio climb: team INEOS Grenadiers initially set the pace until reigning world champion Julian Alaphilippe launched the first attack with 6km to go.
The Frenchman was immediately joined by the other pre-race favourites, including Mathieu van der Poel and defending champion van Aert.
On the following technical descent a group of around 20 riders remained in contention, until Stuyven pulled away from the leading group and held on in front.
"If it’d had gone to the line, I could have finished fifth or tenth but I preferred to go-all in, so I took the biggest victory of my career," Stuyven commented.
"Eight times out of ten you get nothing but there are two times when you can win. It’s amazing, the guys put me in the perfect position on the important part of the parcours. My legs were completely empty but if you win by a mile or a metre, it’s enough."
Van der Poel explained why he didn't follow Alaphilippe and van Aert on the final climb:
"Like everyone says, it’s a very difficult race to win. It’s not easy to make a gap on the Poggio because the speed is so high there that it’s just too difficult to really go away alone. Then it becomes technical in the end."
Van Aert praised fellow Belgian Stuyven for the timing of his attack at the bottom of the descent, but wasn't happy with his sprint:
“Of course a lot of guys were looking at me but I just came up short. In the end Caleb [Ewan] was a bit faster than me in the sprint from our group. It’s always a difficult final few kilometers but today I gambled wrong."
"It was a bittersweet Milano-Sanremo for me," said Sagan.
"On the one hand, I'm happy because I'm feeling better and my form is gradually improving, although there is still work to be done to reach a top level. On the other hand, I'm a bit angry because it was another Milano-Sanremo where I missed the chance to get a victory."