Tour de France: Uneasy Chris Froome keen to extend lead before TT

After Monday's rest day, the reigning Tour champion says the Stage 20 race against the clock will be the last opportunity for any overall contender to make a bid for the yellow jersey

Yellow jersey leader and Team Sky rider Chris Froome of Britain during a media conference during a rest day.

Chris Froome has said he will not feel serene during Saturday's time-trial in Marseille in the penultimate Tour de France stage unless he can take more time out of his rivals beforehand.

The Stage 20 race against the clock will be the last opportunity for any overall contender to make a bid for the yellow jersey.

And even though Froome is widely considered a better time-trialist than his rivals, and he currently leads the race by 18 seconds from Fabio Aru, the Briton said he would want more of a buffer to feel genuinely secure.

"I wouldn't be sleeping easy" Froome said if his advantage did not improve before Saturday. "We always knew it was going to be a close race and that's exactly what it is," said the 32-year-old reigning champion.

"This was to be expected and I knew that every stage, every single second is going to count."

Three riders currently sit within 30 seconds of Froome - Aru at 18, Romain Bardet at 23 and Rigoberto Uran at 29 - with fourth placed Dan Martin only 1 minute, 12 seconds further back.

But it is Uran who Froome fears most as the Colombian is usually the best time-trialist of the Sky team leader's closest competitors.

"Each rival presents different threats. If you look at Fabio Aru, he won the first mountain-top finish on the Planche des Belles Filles.

"Perhaps he didn't have such a good day a couple of days ago, [but] he's been strong in the third week [of a Grand Tour] before. We'll have to wait and see how he goes.

"Romain Bardet has always been strong in the last week of a Grand Tour and he also has the team [AG2R] to back him up, as we saw yesterday - he put me under a lot of pressure yesterday and we really had to use the whole team just to control that situation.

"Rigoberto Uran may be more of the dark horse who just slips under the radar a little bit.

"He's probably the strongest time-trialist of this group of GC riders, so with Marseille in mind he's a big threat."

This Tour has been far from plain-sailing for Froome, who crashed in the first week and has had two mechanical problems at crucial times in mountain stages over the past week.

He admitted that when he had such a difficulty on Sunday, and had to stop to get a spare wheel off teammate Michal Kwiatkowski while his rivals rode off up the road, he feared a fourth Tour victory was slipping away.

"I think it dawned the second AG2R put the hammer down yesterday and I was standing still on the side of the road with Kwiato trying to change my back wheel, I knew then already that this could be the end of my fight for the yellow jersey.

"So I'm just incredibly grateful obviously the way my teammates responded under pressure there and that I had the legs to get back to that main group by the top of the climb.

"Had I not got there, that could have been the end of the race for the overall for me."