Team Sky's Bradley Wiggins retained his overall lead on a tenth stage won by Thomas Voeckler (Europcar) as the Tour de France hit the high mountains for the first time this year.
Voeckler triumphed after being part of a 25-man break which went clear after a frantic opening to the day, getting the better of Michele Scarponi (Lampre-ISD) and Jens Voigt (RadioShack-Nissan) as five of the original group fought out the finish.
Luis León Sánchez (Rabobank) was fourth and Dries Devenyns (Omega Pharma-QuickStep) fifth, with the peloton crossing the line three minutes and 16 seconds later.
The top of the general classification is unaltered; Wiggins is 1:53 ahead of reigning champion Cadel Evans (BMC Racing), with Chris Froome (Team Sky) a further 14 seconds back in third.
The 194.5 kilometres stage from Macon to Bellegarde-sur-Valserine provided the latest test for Team Sky in defence of Wiggins' advantage - and they stood firm in the face of a big attack from fourth-placed Vincenzo Nibali.
That came on the tricky descent of the hors category Col du Grand Colombier, 43km from the finish, as the Italian threw down the gauntlet.
Widely regarded as the best descender in the peloton, Nibali attacked immediately after cresting the summit and was able to open up an advantage of over a minute on the yellow jersey group. He was helped by Liquigas-Cannondale team-mate Peter Sagan, the green jersey holder having been part of the original escape.
Porte plays key role
However Team Sky refused to panic and, despite seeing Michael Rogers drop back with a puncture early on the descent, gradually began to reel in Nibali.
That was due to Richie Porte who produced a superb turn on the front which enabled them to catch Nibali with 20km remaining, just before the final climb of the day up the Col de Richemond.
The run-in to the finish from there saw a battle of attrition between the five riders up front but it was Voeckler who timed his late kick perfectly to land the spoils.
"We were fortunate that we got the right breakaway away," said Wiggins afterwards. "We were prepared to lose the jersey if need be to [Michele] Scarponi who was the best-placed up there.
"This is about being in yellow in Paris and if that means sacrificing the next days and keeping the boys back a bit [then so be it]. Fortunately that came back once we hit the climb and we kept the jersey.
"I was waiting for Nibali to start playing his joker card and he did. Fortunately he went solo and we knew he’d have to have some good legs to stay clear on the next climb and then down into the valley.
"We do have to gamble a little bit here and we can’t just chase everything that moves. We didn’t panic and we got down and rode hard on the next climb and got him back. It all worked out."
Wiggins will on Thursday become the first Briton to wear the leader's yellow jersey for four days in one Tour de France, beating the previous best of three days set by Chris Boardman in 1994 and David Millar in 2000.
And he expressed his delight at the fact that his exploits are continuing to raise the profile of cycling back home, adding: "We’re in a massive bubble here but I know what the Tour’s like as I sat at home and watched it myself last year!
"I know how much people follow it and it’s fantastic that cycling is becoming more popular and more mainstream with the exploits of Chris Hoy on the track. It’s fantastic for our sport and for sport in the UK."
The race now heads into the Alps with a short but brutal-looking stage from Albertville to La Toussuire Les Sybelles which features two hors category climbs before the summit finish.
"It's the toughest day of the race, so it's going to be a big day," said Wiggins.
Sports Director Sean Yates was also mindful of Thursday's stage when we caught up with him.
He said: “It was a nice scenario compared to what it could have been. We wanted a relatively easy day ahead of tomorrow and we were happy to see a big group go clear with no one dangerous in it.
“When they hit the Colombier we were able to control it and maintain the gap. There was no need to close it down but the circumstances of the race made it go a lot faster.
“Nibali attacked on the downhill and we brought him back. After the Dauphine there had been a lot of talk about it. Mick had a puncture on the descent which was unfortunate but we had the bodies up there to handle the situation which was good."