Laruns, France (AFP) – Britain's Geraint Thomas stretched his Tour de France yellow jersey lead on Friday as Slovenian Primoz Roglic won the 19th stage in controversial fashion to push defending champion Chris Froome off the virtual podium.

Thomas, who has held the race lead since stage 11 having won back-to-back stages in the Alps, finished second on the final stage in the high mountains at 19secs behind Roglic after the Lotto-Jumbo rider had launched a series of small attacks before the summit of the Aubisque.

The Welshman's final sprint to clinch second place earned him six bonus seconds, which increased his overall lead on Dutch rival Tom Dumoulin (Sunweb) to 2min 05secs ahead of the penultimate-stage time trial on Saturday.

Roglic moved up to third overall at 2:24 behind Thomas, with Froome now fourth at 2:37.

But while the 28-year-old Slovenian celebrated, Dumoulin was furious at the finish, claiming Roglic "used the slipstream of the motorbike" that had moved in front of him shortly after the summit to build an advantage which, in the end, proved decisive.

Asked to confirm the allegation, Roglic said: "What can I say? I can't comment on things on which I don't have influence over.

"I don't see where the problem is."

Roglic, a former ski jumper, was a constant thorn in the side of Team Sky on the final climb, where his accelerations left four-time champion Froome struggling to hold the wheel on several occasions.

The Slovenian redoubled his efforts shortly after cresting the summit, defying the shrouds of mist to accelerate away from Thomas, Froome, Dumoulin, Spaniard Mikel Landa and Frenchman Romain Bardet to leave them in a desperate chase on the 20 km descent to the finish.

Later, as the accusations poured in, Thomas voiced his suspicions, saying: "All of a sudden it seemed Roglic got a gap.

"The way he did get the gap was a little surprising... but I didn't actually see it myself.

"I was concentrating on the corners, following Tom's wheel. There has been an issue with motorbikes getting too close, but I didn't see it."

Although Thomas's yellow jersey bid was not at stake, except in the event of catastrophe, Sky are desperate to see Froome finish among the podium places in Paris on Sunday and were in no mood to give Roglic a free run to the finish.

Froome managed to limit the damage by following wheels most of the way down before finishing eighth and last from the seven-man group of favourites who crossed the line 19secs behind Roglic.

Fans will be expecting Froome, a six-time Grand Tour champion, to overcome his 13-sec deficit to Roglic and secure a place in the top three.

But Roglic, who only took up cycling six years ago, is no slouch in the race against the clock. Six of his 22 professional wins are from time trials, including one from the Giro d'Italia in 2016.

"The only thing I can focus on in the time trial is myself," added Roglic.

Frenchman Julian Alaphilippe, meanwhile, did enough over the first two big climbs, the Col d'Aspin and the Col du Tourmalet, to secure the 'King of the Mountains' polka dot jersey.

"It's exceptional," said Alaphilippe after finishing 36th at 18:38 behind Roglic.

"It was my dream to win a stage, now I've won two and I've got the polka dot jersey on my shoulders. It's an incredible feeling."

Slovakian Peter Sagan also battled through a final, gruelling day in the mountains, finishing 38:23 behind Roglic to secure his sixth green jersey for the points competition.