Bob Jungels produced a spectacular solo effort to win Liege-Bastogne-Liege, the oldest of the five monument classics.
Jungels (Quick-Step Floors) attacked at the top of the climb of La Roche aux Faucons with 20km remaining and time-trialled his way to the finish line in Ans to win by 37 seconds.
His break looked unlikely to succeed at first, with all of the race favourites together in the lead group and the hardest climbs all out of the way.
But most of the leading contenders ended up marking one another and Jungels was able to build an advantage of nearly a minute at one point.
Jelle Vanandert came closest to catching him, but his attack would only ever see the deficit cut to around 25 seconds before he faded on the final slopes.
That left Jungels on his own at the finish, where he had time to celebrate a first classic win in the 104th edition of the race known as La Doyenne.
Canada's Michael Woods (EF Education First/Drapac) claimed second ahead of Romain Bardet (AG2R La Mondiale) and Fleche Wallonne winner Julian Alaphilippe, a team-mate of Jungels.
Liege-Bastogne-Liege result:
1 Bob Jungels (Lux) Quick-Step Floors 6hr 24min 44sec
2 Michael Woods (Can) EF Education First/Drapac +37s
3 Romain Bardet (Fra) AG2R La Mondiale same time
4 Julian Alaphilippe (Fra) Quick-Step Floors +39s
5 Domenico Pozzovivo (Ita) Bahrain-Merida all same time
6 Enrico Gasparotto (Ita) Bahrain-Merida
7 Davide Formolo (Ita) Bora-Hansgrohe
8 Roman Kreuziger (Cze) Mitchelton-Scott
9 Sergio Henao (Col) Team Sky
10 Jakob Fuglsang (Den) Astana