Race leader Tony Martin fractured his collarbone in a late crash on stage six of the Tour de France as team-mate Zdenek Stybar escaped to a solo victory.
Martin (Etixx - Quick-Step) fell after touching wheels with the rider in front of him around 900m from the finish in Le Havre and brought down several others, including yellow jersey hopefuls Vincenzo Nibali (Astana), Nairo Quintana (Movistar) and Tejay van Garderen (BMC Racing).
While all three were able to remount and finish without serious injury, Martin was not so lucky and had to be helped over the finish line by team-mates.
The 30-year-old German initially hinted he would try to remain in the race when tweeting: "Collarbone is broken. We will discuss further steps." However, his team later confirmed he required surgery and would not start Friday's seventh stage.
Martin's exit will see the race lead passed back to Chris Froome (Team Sky), who was also caught up in the crash but somehow managed to avoid falling.
Because the incident happened inside the last 3km, all those involved or held up by it were awarded the same time on the day, meaning Froome is 13 seconds ahead of second-placed Van Garderen in the general classification and 15 seconds in front of third-placed Peter Sagan (Tinkoff-Saxo).
Alberto Contador (Tinkoff-Saxo) remains 36 seconds down on Froome in seventh, while Nibali is 1min 38sec back and Quintana 1min 56sec adrift.
Stybar (Etixx - Quick-Step), meanwhile, escaped from a clutch of rivals just below the summit of a late climb and hung on over the 500m of flat to the finish to win by two seconds from Sagan in second and Bryan Coquard (Europcar) in third.
Martin said: “I was extremely unlucky. I can't really remember what happened. I touched the wheel of the rider ahead of me. It's the Tour, luck and bad luck are very close together. It's often the way accidents happen. You're not going that fast and then you fall over each other with all your weight.”
The 191.5km sixth stage had been a sedate affair until the final 1.5km, when the road reared up sharply for an 850m climb leading to a flat final 500m.
Martin's fall set off a chain reaction, with Nibali being brought down and in turn taking Quintana and Van Garderen with him. Froome was also next to the trio and while Nibali collided with him with force, the Briton somehow managed to stay upright.
While Martin writhed in agony, Stybar accelerated with around 700m to go and opened up a lead of around 50m of the rest of the pack.
Sagan was well-positioned to chase but opted not to in order to avoid dragging other rivals into contention, and in the end he paid the price with his third runner-up finish of the race.
Stybar said: "Of course, it feels really great. I think everyone who is participating here in France they wish to win a stage. It was my big dream."
The Tour continues on Wednesday with a 190.5km flat stage from Livarot to Fougeres that should end in a bunch sprint. Read more about it in our race guide.
Stage six results
1 Zdenek Stybar (Cze) Etixx – Quick-Step, 4:53:46
2 Peter Sagan (Svk) Tinkoff-Saxo, +2secs
3 Bryan Coquard (Fra) Europcar, st
4 John Degenkolb (Ger) Giant-Alpecin, st
5 Greg van Avermaet (Bel) BMC Racing, st
6 Tony Gallopin (Fra) Lotto Soudal, st
7 Edvald Boasson Hagen (Nor) MTN-Qhubeka, st
8 Davide Cimolai (Ita) Lampre-Merida, st
9 Julien Simon (Fra) Cofidis, st
10 Gorka Izagirre (Esp) Movistar, st
General classification
1 Tony Martin (Ger) Etixx - Quick-Step, 22:13:14
2 Chris Froome (GB) Team Sky, +12secs
3 Tejay van Garderen (USA) BMC Racing, +25
4 Peter Sagan (Svk) Tinkoff-Saxo, +27
5 Tony Gallopin (Fra) Lotto Soudal, +38
6 Greg van Avermaet (Bel) BMC Racing, +40
7 Rigoberto Uran (Col) Etixx – Quick-Step, +46
8 Alberto Contador (Esp) Tinkoff-Saxo, +48
9 Zdenek Stybar (Cze) Etixx – Quick-Step, +1:04
10 Geraint Thomas (GB) Team Sky, +1:15