Peter Sagan (TotalEnergies) was forced to abandon his final Paris-Roubaix after an early crash, suffering a concussion after a head impact.
The 2018 champion fell heavily in a spill on the second of 29 cobblestone sectors after just over 100km of racing.
He was sent flying over his handlebars as the crash occurred around 30 riders from the front of the bunch on a fast part of the three-star sector between Viesly and Quiévy.
Sagan lay in the grass by the side of the cobbles and took a long time to get to his feet. His team soon confirmed he had climbed into the team car and would play no further part in the race.
"End of the race for Peter Sagan," was the succinct statement issued by TotalEnergies at the time, before an update after the race had finished.
"Reassuring news on Peter Sagan. Victim of a crash, he suffers from wounds and a concussion. The results of the tests undertaken at hospital are reassuring. Now for some rest."
Sagan won Paris-Roubaix in 2018 with a blistering attack in which he powered away from his rivals and picked off the breakaway one-by-one, finishing with last survivor Silvan Dillier in a two-up sprint in the Roubaix velodrome.
Sagan has struggled for his former strength in recent years, setting the 2023 campaign as his last on the road. However, it has been a bruising one so far with Sagan now abandoning two Monuments he has won in the space of two Sundays.
The Roubaix abandon follows the same scenario from the Tour of Flanders last week, where he was taken out in the mass crash caused by Filip Maciejuk.
It has been a nightmare day so far for TotalEnergies, who have also lost Daniel Oss and Maciec Bodnar after failing to make the day's breakaway.