Chris Froome’s hopes of winning the Vuelta a Espana took a severe blow on stage 15 after he was caught out by an early attack involving race leader Nairo Quintana and lost 2min 43sec.
Froome (Team Sky) hung on to second place in the general classification, but the result leaves him 3min 37sec adrift of Quintana (Movistar) overall with just two summit finishes, one time trial and three sprint stages remaining.
The attack was initiated by Alberto Contador (Tinkoff) 6km into the 118.5km day and Quintana was among 14 riders who reacted quickly to enough to follow.
Froome's team-mates tried to chase them down but were unsuccessful and the gap between the breakaway and the peloton steadily grew to three minutes.
The Briton's prospects improved when strong pace-setting from Orica-BikeExchange and Astana reduced the deficit to two minutes leading on the to the 14.5km climb to the summit finish at Aramon Formigal, but while Quintana glided up the ascent, Froome looked devoid of energy and the gap grew back out.
The stage was won by breakaway rider Gianluca Brambilla (Etixx - Quick-Step), who managed to match Quintana's electric pace on the final climb and then defeated the Colombian in a sprint for victory.
Contador (Tinkoff) was dropped by Quintana and Brambilla with 1.5km to go and finished 34 seconds down in sixth on the day, which was enough to lift him back into fourth overall, albeit 4min 2sec adrift of the red jersey.
Orica-BikeExchange pair Esteban Chaves and Simon Yates were also caught out by the breakaway and spent much of the day working with Froome.
Chaves was strong enough to attack on the final climb and limited his losses to Quintana to 1min 56sec, leaving him 3min 57sec down in third overall, but Yates finished just behind Froome and slips to 5min 7sec down in fifth.
Froome's failure to follow the attack was compounded by the fact the subsequent chase had the side-effect of dropping all but two of his Team Sky team-mates.
He tried to slow the peloton down to allow them to catch back up, but the Movistar riders in the bunch cleverly upped the pace and Froome's team-mates never regained contact, which left him dependent on other teams to chase Quintana.
Froome started the day 54 seconds down on Quintana and had looked well-placed to overhaul the race leader on stage 19's 37km individual time trial.
However, he will now also have to take substantial amounts of time on the summit finishes on stages 17 and 20 to stand any chance of winning the red jersey.
The Vuelta continues on Monday with a 156.4km 16th stage from Alcaniz to Peniscola, which should end in a sprint. Find out more about the route in our race guide and follow the action with our live blog from 1pm BST.
Stage 15 result
1 Gianluca Brambilla (Ita) Etixx - Quick-Step, 2:54:30
2 Nairo Quintana (Col) Movistar, +3sec
3 Fabio Felline (Ita) Trek-Segafredo, +25
4 Kenny Elissonde (Fra) FDJ.fr, +28
5 David de la Cruz (Esp) Etixx - Quick-Step, +31
6 Alberto Contador (Esp) Tinkoff, +34
7 Davide Formolo (Ita) Cannondale-Drapac, +53
8 Matvey Mamykin (Rus) Katusha, +1:16
9 Esteban Chaves (Col) Orica-BikeExchange, +1:53
10 Michele Scarponi (Ita) Astana, +1:59
Selected others
18 Chris Froome (GB) Team Sky, +2:40
21 Simon Yates (GB) Orica-BikeExchange, +2:45
General classification
1 Nairo Quintana (Col) Movistar, 61:36:07
2 Chris Froome (GB) Team Sky, +3:37
3 Esteban Chaves (Col) Orica-BikeExchange, +3:57
4 Alberto Contador (Esp) Tinkoff, +4:02
5 Simon Yates (GB) Orica-BikeExchange, +5:07
6 Samuel Sanchez (Esp) BMC Racing, +6:12
7 Andrew Talansky (USA) Cannondale-Drapac, +6:43
8 Davide Formolo (Ita) Cannondale-Drapac, +7:17
9 David de la Cruz (Esp) Etixx - Quick-Step, +7:23
10 Michele Scarponi (Ita) Astana, +7:39