Britain's Chris Froome lost ground on Vuelta a Espana leader Alberto Contador as Przemyslaw Niemiec won stage 15.
Froome made seven seconds on Contador on Saturday but lost the same amount on Sunday's 152.2km race from the northern city of Oviedo, which ended in a summit finish at Lagos De Covadonga.
The 29-year-old is tied for third overall, 80 seconds off the pace.
Spain's Contador, 31, said: "Froome is the strongest rival I have come across and you can never count him out."
Stage winner Niemiec was part of an early breakaway group and held on for his first Grand Tour stage victory.
"It is an incredibly happy day for me," said the Lampre Merida rider, who broke clear on a gruelling 12.2km hors category climb towards the finish.
"We had thought about resting for tomorrow's stage, but once I was in the breakaway I saw we had quite an advantage and everyone was working together to get to the end."
The Spanish trio of Contador, Alejandro Valverde and Joaquim Rodriguez repeatedly attacked in an attempt to distance Froome on the final climb, but Contador was disappointed not to make more of a dent in the Sky man's bid for a first Vuelta victory.
"It was perhaps a bit of shame to not open up the distance more on Froome because with a rider of that quality you always have to try and have as much of a gap as possible," he said.
Valverde finished second, five seconds ahead of fourth-placed Contador, but cut the two-time Vuelta winner's lead by 11 seconds to 31 seconds, thanks to time bonuses.
There are six stages remaining, starting with Monday's 160.5km mountainous race from San Martin del Rey Aurelio, which features five mountain climbs and has a summit finish at La Farrapona.
Stage 15 result:
1. Przemyslaw Niemiec (Pol/Lampre) 4hrs 11mins 9secs
2. Alejandro Valverde (Spa/Movistar) +5secs
3. Joaquim Rodriguez (Spa/Katusha) Same time
4. Alberto Contador (Spa/Tinkoff-Saxo) +10secs
5. Fabio Aru (Italy / Astana) +17secs
6. Chris Froome (GB/Team Sky) Same time
7. Daniel Martin (Ire/Garmin) +28secs
8. Warren Barguil (Fra/Giant) +44secs
9. Rigoberto Uran (Col/Omega Pharma-Quick-Step) +1min
10. Giampaolo Caruso (Ita/Katusha) +1min 2secs
Overall classification after stage 15:
1. Alberto Contador (Spa/Tinkoff-Saxo) 58hrs 31mins 35secs
2. Alejandro Valverde (Spa/Movistar) +31secs
3. Chris Froome (GB/Team Sky) +1min 20secs
4. Joaquim Rodriguez (Spa/Katusha) Same time
5. Fabio Aru (Ita/Astana) +2mins 22secs
6. Rigoberto Uran (Col/Omega Pharma-QuickStep) +2min 57secs
7. Daniel Martin (Ire/Garmin) +4mins 55secs
8. Samuel Sanchez (Spa/BMC Racing) +5mins 2secs
9. Robert Gesink (Ned/Belkin)+5mins 11secs
10. Warren Barguil (Fra/Giant) +6mins 36secs