CHRIS Froome surrendered the yellow jersey to Fabio Aru as Romain Bardet won stage 12 of the Tour de France in Peyragudes.

Three-time Tour winner Froome faded badly on the brutal final climb of the 214.5km stage from Pau, while Aru finished third to take the final bonus seconds on offer.

The Italian national champion now leads the Tour by six seconds from Froome, with Frenchman Bardet closing to within 25 seconds of yellow in third place overall.

Astana's Aru will wear the yellow jersey for the first time in his career, while Froome has handed it over for the second time in his, having also lost it after stage four in 2015 before reclaiming it at the end of stage seven and carrying it to Paris.

But that came in very different circumstances and Froome cut a dejected figure as he sat on his turbo trainer after the stage.

The British rider said: "It was very, very tough at the finish. I didn't have the legs in the final – but there's still a long way to go. I just have to applaud Romain Bardet for winning the stage and also Fabio Aru for getting the yellow jersey."

A tough day in the mountains finished with a climb of the airstrip at Peyragudes, only a few hundred metres long but with gradients nearing 20 per cent.

The group of favourites came to the foot of the climb together but, after Aru struck out first, Froome struggled to respond.

AG2R La Mondiale's Bardet timed his attack to perfection, taking victory ahead of Aru and Colombian rider Rigoberto Uran of Cannondale-Drapac, both two seconds back but picking up bonus seconds.

It was a third career stage win for Bardet, who finished second overall last year.

He said: "I'm feeling very happy, for sure. This was maybe the hardest (win) to get but I will try to enjoy it. Tomorrow is another very hard stage and though I'm here for stage wins, I'm here for the overall too, so we have to stay focused."

Froome was left trailing in their wake, coming over the line in seventh place some 22 seconds behind Bardet, beaten to the line by his team-mate Mikel Landa, Irishman Dan Martin and South African Louis Meintjes.

Orica-Scott's Simon Yates finished ninth in the young riders' white jersey but the Lancastrian surrendered 20 seconds to his rival Meintjes.

Team Sky had held the yellow jersey since Geraint Thomas' time trial win in Dusseldorf on the opening day.

Froome began the day with an 18-second lead over Aru and 51-second advantage over Bardet but the picture looks radically different ahead of Friday's short stage from Saint-Girons to Foix, which has the potential to change the shape of the race once again.

The fireworks in the fight for yellow came after Steve Cummings fell short in a bid for a solo win on the 50th anniversary of Tom Simpson's death during the 1967 Tour.

The Team Dimension Data rider had been part of a 12-man break which went away early on the stage and he attacked solo on the climb of the Port de Bales, staying clear until midway up the Col de Peyresourde, caught with eight kilometres of the stage remaining.

Cummings said: "Today was a chance, I just needed the right combination. Unfortunately Sky kept the gap too small. I needed six or seven minutes coming to the Port de Bales, not four. I committed but I didn't have the legs."