Julian Alaphilippe dug deep to keep the overall Tour de France lead on Sunday as Simon Yates captured his second stage of this year's race and defending champion Geraint Thomas kept his title hopes alive after a late surge.

Sunday's stage winner was Simon Yates of Team Mitchelton. Scott also won Thursday's stage, but his twin brother Adam Yates lost time again.

Incredible Frenchman Alaphilippe

Few believed Frenchman Alaphilippe would emerge from two daunting summit finishes in the Pyrenees with the lead, but at the stage finish he donned the yellow jersey for an astonishing 11th time as reward for his swashbuckling performances that have lit up this tour.

"I expected to lose a bit of time today. I'm delighted that I'm still in the yellow jersey. I gave my best to fight and retain the lead," said the 27-year-old world No.1 rider from Team Deceuninck-Quick-Step

"We knew it would be a hard day, I paid for my efforts in the finale," admitted Alaphilippe who turned up at the Tour after multiple wins including the Fleche Wallonne and Milan-San Remo.

Thomas struggled on the final climb into the clouds, but then closed the gap on the leader to one minute and 35 seconds by dropping him with a late burst after initially looking like he was going to lose precious time on the overall leader.

"Tactics-wise, we were stuck a bit between a rock and a hard place, but the positive is that the legs responded a little bit better today. It was a decent day all round to be honest," Thomas said after the stage.

"I was suffering at times and the rest day will be welcome for everyone," added Thomas of Monday's second rest day before the Tour heads north towards the Alps for a final three days of high altitude reckoning.

Ineos sports director Nicolas Portal said his British team was "fine" with where they were so far.

"We're in second place with G (Thomas)" said Portal. "We were not expecting this from Alaphilippe, he's been imperious."

"It's exciting, he's the man of the tour so far, but there's a long way to go and we are hoping he blows," he said.

Simon aims gold at Tokyo 2020

Simon, who won the multi-stage cycling race Vuelta a Espana in Spain, said he had mixed feelings about his performance.

"I came here to help my brother Adam, and that hasn't gone to plan," he admitted after his twin had a poor time in the Pyrenees.

"But I had a second objective and that was to win a stage. I've now won two and who knows, maybe there's third one up the road," said Simon, adding that he would target winning the Tour de France possibly in 2021 after going for gold at the Tokyo 2020 Olympic Games road race.

Stage 15 featured a 185-km mountain ride from Limoux to Foix Prat d'Albis in France on July 21.

Top 3 riders from stage 15

1. Simon Yates (UK/Team Mitchelton-Scott) 4 hours 47 minutes and 4 seconds

2. Thibaut Pinot (France/Team Groupama-FDJ) +33 seconds

3. Mikel Landa (Spain/Team Movistar) same time

General ranking of Top 3 riders after stage 15

1. Julian Alaphilippe (France/Team Deceuninck-Quick-Step) 61 hours 0 minutes and 22 seconds

2. Geraint Thomas (UK/Team Ineos) +1 minute and 35 seconds

3. Steven Kruijswijk (Netherlands/Team Jumbo-Visma) +1 minute and 47 seconds

(With input from agencies)