Chris Froome
Froome held off the challenge of Quintana with three mountain stages remaining. Getty Images

Chris Froome came through his first Alpine test with his Tour de France lead intact after another thrilling day of attacks.

The Team Sky rider finished with closest challenger Nairo Quintana at Pra Loup as both took time out of their other rivals.

Froome still leads the Colombian by three minutes 10 seconds with three more days in the Alps before he can celebrate a second Tour triumph.

"I was pushed to the limit out there and I can expect more of the same over the next three days," the Briton said.

"When you have got General Classification riders attacking 50-60kms into the race you know you are going to be in for a hard day.

"There are still three races left so I know Quintana is going to try and attack every time he can. I think he will be attacking right up until we get to Paris.

"I heard Contador crashed which is bad news for him, but I'm focussing on Quintana and Valverde as they are the closest guys to me."

Germany's Simon Geschke claimed the biggest win of his career with a fine solo ride to win stage 17.

Froome was left exposed for the final climb as his team-mates had been dropped and Quintana had three fellow Movistar riders for company.

But when Quintana attacked for the second time with around a mile left Froome immediately went with him and then kicked himself.

The duo finished seven minutes 16 seconds behind Geschke but Froome will be delighted to have ticked another potentially dangerous stage off.

Alejandro Valverde moved into third place overall after American Tejay van Garderen was forced to quit, but he is four minutes nine seconds back.

Froome's team-mate Geraint Thomas moved up to fourth, and close to a podium place, after Alberto Contador crashed.

The Spaniard went down on the hair-raising, 60mph descent of the Col d'Allos and lost over two minutes.

Thomas is six minutes 34 seconds behind Froome on the Yellow Jersey classification.

American Tejay Van Garderen abandoned in tears having been hit by an illness.

The BMC rider, who started three minutes 32 seconds behind Froome, was struggling from the start in Digne-Les-Bains and was soon dropped by his yellow jersey rivals.

And despite briefly regaining contact with the peloton he popped off the back on the third climb of the day and was forced to quit before being consoled by his team managers.

Froome's Sky team, meanwhile, have been urged to provide more information as the row with France 2 over their doping slurs rumbles on.

The French network claimed, via physiologist Pierre Sallet, that the Nairobi-born rider's crushing win on stage 10 was abnormal.

Sallet sad he estimated Froome's power-to-weight ration for the climb up La Pierre St Martin as 7.04 watts per kilometre, a figure which raised question marks over doping.

Sky's Head of Performance Tim Kerrison has insisted on Tuesday's rest day that the figure was in fact 5.78.

Now Sallet has countered, saying: "I'd be happy if he is unique but we need more information.

"I don't say Froome is a doping athlete. If we have more detail, we can easily say it is a unique profile or doping.

"If the yellow jersey was a French athlete, we would put in the same energy. It's not against Froome. We want to understand."