Nairo Quintana soloed to victory on stage 18 of the Tour de France in Valloire as Egan Bernal raced away from Ineos team-mate Geraint Thomas while they tried to shake off Julian Alaphilippe on the Galibier.

Bernal attacked around three kilometres from the summit of the famed climb and pulled out a lead of 32 seconds over the much-reduced group of favourites to move himself up from fifth to second overall, now five seconds ahead of Thomas.

Thomas had tried a dig of his own, bursting off the front of the group with around two kilometres of the climb but this time Thibaut Pinot and Steven Kruijswijk responded, catching him by the summit, with the effort perhaps only serving to limit Bernal's time gains.

That is sure to reopen the debate over team leadership within Ineos once again.

"We wanted it to be hard but the pace wasn't there," Thomas said. "The call was made for Egan to go and hopefully that would kick it off a bit, but it didn't.

"That's when I went as well, just to test. But at least Egan gained some time on everyone else."

The attacks served to distance Alaphilippe who struggled on the steepest gradients, but the Deceuninck-Quick Step rider used his outstanding descending skills to catch the group on the long drop to the finish and even rode through to try a move of his own off the front before being reeled in.

The Frenchman did more than enough to keep his yellow jersey for another day, with his lead now 90 seconds over Bernal, who sits five seconds clear of Thomas in third.

Jumbo-Visma's Kruijswijk dropped one place to fourth, one minute and 47 seconds down, three seconds ahead of Groupama-FDJ's Pinot in fifth.

Alaphilippe will be happy to have hung on for one more day, but his rivals will have taken note of his struggles on the climb as he quickly lost time before the downhill finish worked in his favour.

Dan Martin has slipped back to 19th overall, after coming home 70th today.

A 105th place finish for Nicolas Roche means he's now 33rd in overall classifications.