Chris Froome extended his lead of the Tour de France by finishing second to Peter Sagan on stage 11 following an instinctive late attack.
The day had looked set to end in a bunch sprint, but then Sagan (Tinkoff) accelerated out of a wind-battered peloton alongside team-mate Maciej Bodnar with 12km to go and both Froome and Team Sky team-mate Geraint Thomas reacted quickly enough to follow.
The quartet swiftly pulled away and managed hang on to the finish in Montpellier, where Sagan comfortably defeated Froome in a sprint for the line.
The peloton followed six seconds later, which, combined with the six bonus seconds Froome received, stretches his lead over second-placed Adam Yates (Orica-BikeExchange) at the top of the general classification to 28 seconds.
Dan Martin (Etixx - Quick-Step) remains third but is now 31 seconds adrift, while Nairo Quintana (Movistar) stays fourth but drops to 35 seconds down.
Sagan said: "It was something crazy that happened. I didn't believe we attacked like that. Froomey and Geraint Thomas came with us and I said we are too strong, they are never going to catch us. We pulled very hard and it happened. It's unbelievable
"Today everybody was, 'It's crazy wind', but the crazy was the just the last 15km, or 12km. It was not planning. You have to stay at the front and the bunch was going to split for sure, but to go in a breakaway with the green jersey, yellow jersey, and two guys like Bodnar and Thomas, you cannot plan that. I just happened. Crazy."
Stage 11 covered 162.5km of mainly flat terrain but high winds created a constant threat of splits in the peloton and the day consequently turned out to be one of the toughest and most stressful of the race so far.
The bunch broke apart multiple times as Team Sky and Tinkoff repeatedly accelerated in the crosswinds, but the peloton was almost all back together with 15km to go and a sprint finish looked certain.
However, Sagan then attacked and when only Bodnar, Froome and later Thomas followed, a gap quickly opened to the rest of the peloton and they stretched it out to a maximum of 26 seconds.
Froome looked to be heading for substantial time gains when Etixx - Quick-Step and Katusha both failed to cut the lead, but then Giant-Alpecin and Lotto Soudal took over the chase and reduced deficit substantially by the finish.
The stage was nonetheless a big and unexpected success for Froome, although it remains to be seen if he feels the effects of his efforts on Thursday's shortened summit finish on Mont Ventoux.
The biggest loser of stage 11 was Joaquim Rodriguez (Katusha), who dropped from fifth to 12th overall after finishing 1min 9sec down on Froome.
Follow stage 12 with our live blog from 11am BST on Thursday.
Stage 11 result
1 Peter Sagan (Svk) Tinkoff, 3:26:23
2 Chris Froome (GB) Team Sky, same time
3 Maciej Bodnar (Pol) Tinkoff, st
4 Alexander Kristoff (Nor) Katusha, +6sec
5 Christophe Laporte (Fra) Cofidis, st
6 Jasper Stuyven (Bel) Trek-Segafredo, st
7 Edvald Boasson Hagen (Nor) Dimension Data, st
8 Andre Greipel (Ger) Lotto Soudal, st
9 Sondre Holst Enger (Nor) IAM Cycling, st
10 Oliver Naesen (Bel) IAM Cycling, st
General classification
1 Chris Froome (GB) Team Sky, 52:34:37
2 Adam Yates (GB) Orica-BikeExchange, +28sec
3 Dan Martin (Irl) Etixx - Quick-Step, +31
4 Nairo Quintana (Col) Movistar, +35
5 Bauke Mollema (Ned) Trek-Segafredo, +56
6 Romain Bardet (Fra) Ag2r-La Mondiale, same time
7 Sergio Henao (Col) Team Sky, st
8 Alejandro Valverde (Esp) Movistar, +1:13
9 Tejay van Garderen (USA) BMC Racing, st
10 Roman Kreuziger (Cze) Tinkoff, +1:28