Primoz Roglic extended his Vuelta a Espana lead after stage 16, where Jakob Fuglsang celebrated his first Grand Tour victory.
Jumbo-Visma rider Roglic already held a lead of two minutes and 25 seconds following the weekend, but he further improved his standing ahead of Alejandro Valverde on the ride to Alto de La Cubilla.
Race leader Roglic was the main benefactor of a day when Astana drove the agenda, with Fuglsang victorious and an attack within the peloton dropping contender Nairo Quintana even further back.
Fuglsang played a key role in reeling an early break back in and then led when a far sturdier break was established later in the day.
He was still within a group of 10 leaders with around 25 kilometres to go and then made a decisive solo move with 4km remaining, quickly establishing a 15-second gap to Tao Geoghegan Hart.
That was enough to secure victory - a first in Grand Tours for the two-time Criterium du Dauphine winner - and the attention instead turned to the peloton.
Tadej Pogacar, in third, managed to stick with Roglic in the first bunch, but Valverde dropped behind, losing another 23 seconds on the leader.
That advantage reached two minutes and 48 seconds at the end of the stage, yet it paled next to the dire straits Quintana found himself in.
The 2016 champion, an established star on the Grand Tour circuit, was just 27 seconds back on the leaders after 13 stages but endured a miserable weekend, before his poor form continued on Monday.
Astana's Omar Fraile stepped on the accelerator in the peloton with 7km remaining and left Quintana behind, seeing him drop to seven minutes and 43 seconds back on Roglic, although still in a competitive sixth with some major hurdles still to clear.
1. Jakob Fuglsang (Astana) 4:01:22
2. Tao Geoghegan Hart (Team INEOS) +00:22
3. Luis Leon Sanchez (Astana) +00:40
4. James Knox (Deceuninck-QuickStep) +00:42
5. Gianluca Brambilla (Trek-Segafredo) +01:12
1. Primoz Roglic (Jumbo-Visma) 62:17:52
2. Alejandro Valverde (Movistar) +02:48
3. Tadej Pogacar (UAE Team Emirates) +03:42
1. Primoz Roglic (Jumbo-Visma) 117
2. Tadej Pogacar (UAE Team Emirates) 92
3. Alejandro Valverde (Movistar) 82
King of the Mountains
1. Geoffrey Bouchard (AG2R La Mondiale) 50
2. Angel Madrazo (Burgos BH) 44
3. Tao Geoghegan Hart (Team INEOS) 29
The final rest day of the race is up next before, on Wednesday, the longest stage of this year's Vuelta. The 219.6km flat ride from Aranda de Duero to Guadalajara could allow for a decisive breakaway at this late stage.