Chris Froome extends his advantage after 17th stage of Tour de France

Race favourite narrowly beats Alberto Contador in a rainy time trial, extending his overall lead.

Alberto Contador gave chase but could not catch Tour leader Chris Froome, above, who finished nine second ahead to win Stage 17.

CHORGES, France // Chris Froome on Wednesday narrowly beat Alberto Contador to win the 17th stage of the Tour de France in a rainy time trial, extending his overall lead.

The British rider was slower than Contador on the first part of the undulating 32km course, from Embrun to Chorges in the French Alps, but gained time over the final section to finish nine seconds ahead of the Spaniard and clinch his third stage win of the race.

Froome, who has also won two mountain stages, made up for last week when he was edged by Tony Martin in the first time trial on Stage 11.

"This is incredible for me," Froome said. "This morning I thought to myself, 'OK, I'm ready to lose a bit of time, because tomorrow will be very hard'. So I'm surprised to win."

Bauke Mollema held second place overall for several stages, but Contador took his place with the Dutchman dropping to fourth.

Joaquin Rodriguez finished the stage in third place, 10 seconds behind Froome – who is 4:34 ahead of Contador overall and 4:51 clear of Contador's teammate, Roman Kreuziger. Mollema is fourth, 6:23 back.

Froome, wearing an aerodynamic black helmet with a thick yellow stripe down the middle, coughed into his right hand as he prepared to start.

When the five-second countdown finished, Froome puffed his cheeks and rolled down the ramp.

The day after narrowly avoiding a crash when Contador fell just in front of him on a long downhill, Froome started cautiously on a circuit that was slippery after some afternoon rain and featured two short, sharp climbs and two quick descents.

"The first downhill was dangerous and very technical, so I didn't want to take any risks," Froome said.

He was two seconds behind Contador at the first time split. The Spaniard was happy to take more risks and continued to open up a gap. It looked to be Contador's day, with Froome 11 seconds behind when reaching the top of the second climb, but the Briton started to claw back at the deficit.

Riders have three gruelling days of climbing in the Alps before Sunday's night-time finish on the Champs-Elysees.

Thursday's 172.5km trek from Gap to L'Alpe-Huez sees two ascents of L'Alpe-Huez – one of the Tour's most famed climbs.

Both of the ascents are known as HC or Hors Categorie, meaning they are so tough, they are considered beyond classification.

Also, there is a treacherously fast descent from the top of Col de Sarenne, which might make Froome a bit nervous after nearly falling on Tuesday.

There are two more HC climbs and two Category 1 ascents on Friday, and Saturday finishes with an HC.

Wednesday's route ascended immediately for 6.4 kms up Cote de Puy-Sanieres, and the first descent featured several hairpins. After that there was a slightly longer uphill drag up Cote de Reallon, followed by a longer descent.

"That's one of the hardest time-trials I've ever done," said Lieuwe Westra, who finished 17th.

"I don't remember anything like it."

American rider Tejay van Garderen, who was 10th, was relieved to finish the stage.

"The entire course, any moment you could make a mistake and slip up – it wasn't just one point," he said. "You had to stay calm and focused."

Follow us