Nairo Quintana claimed a fantastic win in stage 18 of the Tour de France while Julian Alaphilippe held onto the yellow jersey, as Egan Bernal moved ahead of team-mate Geraint Thomas in the general classification standings.
After a remarkable breakaway, Quintana set a new record for the quickest climb of Galibier - the last of three huge peaks in Thursday's stage - conquering it in 22:28.
Though Quintana's third Le Tour stage triumph put him into GC contention with two more summit finishes to go before Paris, it was back in the yellow jersey group where the real drama occurred.
With Bernal having already made his move, Thomas looked set to be closing in on the yellow jersey when he attacked on Galibier, but Alaphilippe recovered with a fantastic descent, overtaking the Team INEOS rider and Thibaut Pinot.
Alaphilippe was caught before the line, though his brilliant effort in the final stretch ensured he ended the stage having dropped just five seconds to second place, which is now occupied by Bernal.
The Colombian was the major mover, with his eighth-place stage finish seeing him leapfrog INEOS team-mate Thomas into second in the GC standings, 90 seconds behind Alaphilippe.
INEOS were without Luke Rowe after his disqualification on Thursday, and 2018 winner Thomas conceded he had little more to give, though was pleased for Bernal's success.
"We wanted a hard pace and unfortunately we ran out of guys," Thomas told ITV Sport.
"The call was made for Egan to go and that kicked it off. I couldn't do much then other than follow. I had a little dig just to see if anything was going to happen and the guys followed me over the top. It was a good day for Egan gaining some time.
"There are two big days now. We knew it would be hard to drop Alaphilippe, but there are two more big days to come."
Romain Bardet's impressive ride saw him finish second, 95 seconds behind Quintana, and the Frenchman now holds a 12-point lead over Tim Wellens in the King of the Mountains standings.
1. Nairo Quintana (Movistar) 5:34:15
2. Romain Bardet (AG2R La Mondiale) + 01:35
3. Alexey Lutsenko (Astana Pro Team) + 02:28
4. Lennard Kamna (Sunweb) + 02:58
5. Damiano Caruso (Bahrain-Merida) + 03:00
1. Julian Alaphilippe (Deceuninck-Quick Step) 75:18:49
2. Egan Bernal (INEOS) +1:30
3. Geraint Thomas (INEOS) +1:35
1. Peter Sagan (Bora-Hansgrohe) 309
2. Elia Viviani (Deceuninck-Quick Step) 224
3. Sonny Colbrelli (Bahrain-Merida) 203
King of the Mountains
1. Romain Bardet (AG2R La Mondiale) 86
2. Tim Wellens (Lotto Soudal) 74
3. Damiano Caruso (Bahrain-Merida) 60
Just two stages remain before the race heads to Paris, and things do not get any easier on Friday. A gruelling 126.5 kilometres stage from Saint-Jean-de-Maurienne to Tignes includes the Category H climb of Henri Desgrange and Category 1 slog up Montee de Tignes, which comes in the final 10km.