Mathieu van der Poel broke his own record time to defend the Paris-Roubaix title after a stunning solo attack.
The Dutch world champion, 29, pounced 60km from the finish and went on to beat the mark he set last year by almost three minutes.
It was his sixth win in a Monument – the name given to road cycling’s five most prestigious one-day races.
“I never could have dreamed of this as a child,” he said, after adding to last weekend’s Tour of Flanders victory.
“I was super motivated this year, I wanted to show off the [rainbow] jersey [as world champion] in a nice way. It goes beyond expectations. I am lost for words to be honest with you, but I am really enjoying this moment.”
Paris-Roubaix is the third Monument of the season, after Milan-San Remo and the Tour of Flanders, with Liege-Bastogne-Liege (21 April) and the Giro di Lombardia (12 October) to come.
Organisers had made tweaks to the notoriously difficult course in a bid to protect riders following a number of recent high-profile crashes.
Belgian rider Wout van Aert, who would have been one of Van der Poel’s main rivals, suffered a broken collarbone and several broken ribs in a heavy crash at the Dwars door Vlaanderen one-day race in March.
But while the race, which includes 57km of perilous cobblestones, was punctuated by a series of bumps and falls, Van Der Poel’s Alpecin-Deceuninck team helped keep him out of danger before providing the platform to launch his attack.
The Dutch rider quickly opened a significant lead as the chasing pack started to battle among themselves for the minor places.
He rode alone into the famous Roubaix velodrome, where the race traditionally finishes, and crossed the finish line in five hours 25 minutes 58 seconds – completing the route at the fastest average speed in the history of the event, which was first held in 1896.
Van der Poel’s Belgian team-mate Jasper Philipsen finished in second place, three minutes behind, pipping Denmark’s Mads Pedersen in a sprint finish.
Fred Wright was the first British rider home, in 13th place in a group four minutes 47 seconds back, while former junior and under-23s winner Tom Pidcock was 17th on his senior debut.
Meanwhile, Britain’s Josh Tarling was disqualified early in the race after being judged to have gained an illegal tow from his Ineos Grenadiers team car as he attempted to rejoin the peloton following a puncture.