In the final five kilometres, Soler saw an opportunity to surge ahead and opened up an unbridgeable gap at the front, with Italy's Filippo Zana and Britain's Max Poole taking second and third, respectively.
"It's a very special victory because I haven’t won a lot with this team and after two years, winning here in La Vuelta is special," Soler said.
"I tried to accelerate several times (on the climb to the Lagos de Covadonga), Max Poole also tried it several times and in the end I was able to take this advantage."
Slovenian Roglic sensed an opportunity in the rainy mountains from Luanco to Lagos de Covadonga, finishing 11th - nine places ahead of O'Connor - cutting nearly a minute off the Australian's overall lead.
Belgian rider Wout van Aert was forced to withdraw from the Vuelta following a crash during a descent, where he sustained injuries to his legs and arms. The accident occurred with more than 50km left in the stage.
At the time of his withdrawal, the 29-year-old was leading both the points and king of the mountains rankings.
