Geraint Thomas was left stunned by the sizzling display of Julian Alaphilippe in the Tour de France's 'race of truth'.
Defending champion Thomas had expected to gain time on the French darling but lost 14 seconds in the Pau 27.2km time trial.
They finished one and two ahead of Belgian Thomas de Gendt (Lotto Soudal) to stay top of the standings in the race for the yellow jersey after 13 of the 21 stages.
Team Ineos leader Thomas is 1min 26sec behind Alaphilippe in the overall standings with Dutchman Steven Kruijswijk (Jumbo-Visma) climbing to third at 2min 12sec.
Alaphilippe's Deceuninck-QuickStep teammate Enric Mas is up to fourth at 2min 44sec with Thomas' lieutenant Egan Bernal dropping to fifth at 2min 54sec.
Thomas admitted he didn’t expect Alaphilippe to beat him in the race against the clock.
“He’s obviously going incredibly well,” said Wales' twice Olympic track gold medallist.
Asked if he thought Classics specialist Alaphilippe was now a genuine challenger to wear the yellow jersey all the way to Paris, Thomas replied with an emphatic yes.
"He’s certainly the favourite, the one to watch, for sure the way he is riding. If he can keep that up he will win," the 33-year-old went on.
But Thomas warned: "There’s long way to go - there are some hard stages to come."
They start with tomorrow's finishing on top of the 2,115m high Col du Tourmalet and Sunday's at the summit of Foix Prat d'Albis.
Alaphilippe said: "I knew that I really could do a good performance on this parcours.
"I just gave everything, the first part was very good for me. I just gave it everything, went full gas and won the stage.
"I'm just so happy and want to enjoy it. To do something like I did shows the confidence and shape I have."
But, asked if he could become the first Frenchman to triumph at the the Tour since Bernard Hinault in 1985, Alaphilippe claimed: "We don't have the team to win."
However, after a pause, he added: "But we ride really aggressively and we try to win."
The time trial caused a shake up at the top of the standings, with Mitchelton-Scott's Briton Adam Yates and UAE Team Emirates' Irishman Dan Martin among the losers.
Martin finished 33rd, 2min 6sec down on Alaphilippe, with Yates one place and two seconds further back.
Yates dropped from seventh to 10th, 3min 55sec down, with Martin 11th a further 20 seconds adrift.
France's other main hope Thibaut Pinot, who was caught out in cross-winds on stage 10, performed well and moved up to seventh, albeit still 3min 22sec off yellow.
Key Events
Thomas shocked by the performance of Alaphilippe
Thomas admitted he didn’t expect Alaphilippe to beat him in the time trial.
“He’s obviously going incredibly well,” said Thomas.
“He’s certainly the favourite, the one to watch, for sure the way he is riding. If he can keep that up he will win.
“But there’s long way to go - there are some hard stages to come.”
Julian Alaphilippe increases lead on Thomas in overall standings
Alaphilippe won the stage by 14sec from Thomas with de Gendt a further 36sec in arrears.
It means Alaphilippe has increased his lead in the general classification over Thomas to 1min 26sec with Steven Kruijswijk climbing to third a further 48sec behind.
Spaniard Enric Mas is up 4th with Thomas’ teammate Egan Bernal having dropped to 5th.
Thomas is beaten by Alaphilippe in key time trial
The incredible Alaphilippe has taken 8sec out of Geraint Thomas in the final kilometer to win the time trial and extend his lead in overall standings to approximately 1min 26sec.
Alaphilippe and Thomas are the fastest men
Quintana has finished in 36min 51 sec but Yates has been more disappointing with a 37min 8sec.
Spaniard Enric Mas will move past the Briton in the overall standings after storming to a time just 22.29sec behind de Gendt.
Alaphilippe is going slightly faster than Thomas with just a few kilometers remaining.
They were the quickest through the third checkpoint, Alaphilippe passing it in four seconds less than Thomas.
Nip and tuck between Thomas and Alaphilippe
Geraint Thomas set the fastest time at the halfway point but the astonishing Alaphilippe beat it by more than six seconds.
Who will finish the stronger?
Great ride from Thibaut Pinot
Pinot has ridden the time trial of his life to be fourth fastest, 13.6sec behind de Gendt. That will move him up the general classification.
Bernal, meanwhile, is feeling it and is set to lose third place in the overall to Steven Kruijswijk, who is flying.
Thomas a second slower at first checkpoint
Dane Jakob Fugslang, who was heavily fancied by bookmakers ahead of the Tour, was 31.42sec slower than de Gendt at the finish.
Yates was a disappointing 50.45sec slower than de Gendt at the second checkpoint.
Thomas has just passed the first checkpoint and was a second behind de Gendt.
Big names are flying
Rigoberto Uran, who finished second overall to Chris Froome two years ago, has matched Porte’s time at the second checkpoint but his fellow Colombian Nairo Quintana was 25sec down.
France’s second darling, Thibaut Porte, was fourth fastest as he attempts to make up time he lost in crosswinds on Monday.
Richie Porte posts second fastest time
He finished just 9.40sec behind de Gendt. That will boost Porte’s morale for the rest of the race and the high mountains to come.
Geraint Thomas is underway
Geraint Thomas has just rolled down the start ramp. Only Alaphilippe. remains to go.
Adam Yates has left the start ramp
Geraint Thomas’ big British rival Adam Yates is on the course. He was seventh in the overall standings, 35 seconds behind Thomas.
Climber Yates, whose twin brother Simon won yesterday’s stage in the Pyrenees, will be attempting not to lose too many seconds to time trial specialist Thomas, as he targets a place on the podium in Paris.
Aussie ace Richie Porte is flying
Porte, a former teammate of Thomas, has crashed out of the last two Tour de France races but he is less than a second behind de Gendt’s time at the second checkpoint.
Spaniard Mikel Landa, one of the best climbers in the world, is attempting to limit his losses. He was 37 seconds behind at the same place.
Another fast-man hits the deck at Tour de France
There’s been another heavy crash with Max Schachmann, who was on the leaderboard, looking bruised, battered and cut as he pedalled slowly towards the finish line.
Breakaway specialist in lead of time trial after sizzling in the sun
Belgium breakaway specialist Thomas de Gendt, who won last Saturday’s stage 13, has set the fastest time of 35min 36sec.
That was 16 seconds quicker than that posted by Danish champion Kasper Asgreen. American Joey Rosskopf was third fastest but it could change with the yellow jersey contenders beginning to line up near the start ramp.
Yellow jersey wearer is feeling the pressure
Home favourite Julian Alaphilippe, who is 72 seconds ahead of Thomas in the general classification, vowed he wouldn’t go down without a fight.
“I feel the pressure of France on my shoulders but I’m going to continue to give it everything,” he pledged.
“As I’ve said, anything now is just a bonus. With the yellow jersey on my shoulders, I think I really have a good reason to hurt myself.
“I’m so motivated, so happy. Whatever happens, it’s been great, but I just want to go as deep as possible and defend the jersey with honour.”
Geraint Thomas' tip for time trial has crashed out
The Welsh wizard had tipped Dutch dynamo Wout Van Aert to win the time-trial.
But the cyclo-cross ace, who had already pocketed a stage of his debut Tour de France, suffered an horrific crash in the final kilometer of the 27.2km race against the clock.
He took a corner too tightly and piled into the barriers and was dragged off his bike. He needed extensive treatment before being taken to hospital for treatment on a suspected hip injury.
Thomas will also be taking risks, saying: “I’ll go all out and see where that puts me. It would be great to win the stage.”
