Vincenzo Nibali saw his overall lead of the Vuelta a Espana cut in half after being dropped on the final climb of stage 16 as French prodigy Warren Barguil claimed his second win of the race.
Nibali (Astana) was unable to respond to an attack from Joaquim Rodriguez (Katusha) 2km out from the summit finish on Aramon Formigal and then could only look on helplessly as Chris Horner (RadioShack-Leopard) and Alejandro Valverde (Movistar) also left him behind as they set off in pursuit.
The Italian eventually crossed the finish line 22 seconds down on Horner and consequently sees his lead over the American in the general classification reduced from 50 seconds to 28 seconds.
Breakaway rider Barguil (Argos-Shimano) pipped Rigoberto Uran (Team Sky) in the narrowest of photo finishes to continue his breakthrough Vuelta with another impressive win.
Barguil doubles up
The 21-year-old had attacked from a large escape group just over 9km out but looked to have lost his opportunity when Uran countered and caught him with just over 1km remaining.
Barguil was able to remain on the Colombian's wheel, though, and regrouped sufficiently enough to beat him by less than a width of a tyre in a tight sprint finish.
"It is a really nice result for me," Barguil said. "My directeur sportif said stay in the bunch and recover for next week, but I had very good legs and I attacked.
"After I saw Uran come back to me I had a little bit of recovery. I was strong in my head for the sprint. Uran is a very strong rider and a win over him is crazy."
The 146.8km 16th stage presented a third consecutive summit finish in the Pyrenees. With breakaway riders having won the previous two, dozens of men were keen to get into the escape and it consequently took 62km for a nine-man group to finally form.
Uran falls short
It later swelled to 23, but Barguil escaped them all on a flat section a third of the way up the 15.8km, category-one final climb and slowly built up a lead of over 30 seconds.
A four-man chase group containing Uran, Dominink Nerz (BMC) and Bartosz Huzarski (NetApp-Endura) set off in pursuit, but despite Uran and later the other two regaining contact, Barguil would not be denied.
Back down the road, after the peloton had been reduced to just a handful of elite riders, Valverde tested Nibali's legs with a short-lived attack 3km out, before Rodriguez launched a much more purposeful burst a kilometre later.
The Spaniard swiftly opened up a handy gap, but following counter-attacks, he crossed the line only three seconds ahead of Valverde and six seconds ahead of Horner.
Stage 16 result
1 Warren Barguil (Fra) Argos-Shimano, 3:43:31
2 Rigoberto Uran (Col) Team Sky, same time
3 Bartosz Huzarski (Pol) NetApp-Endura, +3secs
4 Dominik Nerz (Ger) BMC, +8
5 Jose Herrada (Spa) Movistar, +20
6 Mikael Cherel (Fra) Ag2r-La Mondiale, + 37
7 Maciej Paterski (Pol) Cannondale, st
8 Andre Cardoso (Por) Caja Rural, +40
9 Amets Txurruka (Spa) Caja Rural, +42
10 Chris Anker Sorensen (Den) Saxo-Tinkoff, +45
17 Joaquim Rodriguez (Spa) Katusha, +1:41
18 Alejandro Valverde (Spa) Movistar, +1:44
20 Chris Horner (USA) RadioShack-Leopard, +1:47
26 Vincenzo Nibali (Ita) Astana, +2:09
1 Vincenzo Nibali (Ita) Astana, 64:06:01
2 Chris Horner (USA) RadioShack-Leopard, +28secs
3 Alejandro Valverde (Spa) Movistar, +1:14
4 Joaquim Rodriguez (Spa) Katusha, +2:29
5 Domenico Pozzovivo (Ita) Ag2r-La Mondiale, +3:38
6 Nicolas Roche (Irl) Saxo-Tinkoff, +3:43
7 Thibaut Pinot (Fra) FDJ, +4:37
8 Leopold Konig (Cze) NetApp-Endura, +6:17
9 Samuel Sanchez (Spa) Euskaltel-Euskadi, +7:33
10 Tanel Kangert (Est) Astana, +9:21