Spain's Pablo Castrillo pushed through the pain barrier to take stage 15 of the Vuelta a Espana on Sunday, his second stage win, while Primoz Roglic took more time off race leader Ben O'Connor.
Ireland's Eddie Dunbar (Team Jayco AlUla) produced a hugely gutsy ride to come 14th and hoist himself up to 15th in the general classification.
Castrillo (Kern-Pharma) was part of a leading trio on the gruelling Cuitu Negru climb to the finish and made his move with three kilometres to the end of the 143km ride from Infiesto to Valgrane-Pajares.
In the final kilometre he glanced over his shoulder to see Aleksandr Vlasov (Red Bull-Bora-Hansgrohe) appear through the fog, but Castrillo found another burst of energy to hold off the Russian, with Pavel Sivakov of France coming in third.
Three-times former champion Primoz Roglic finished fifth, coming in 38 seconds ahead of the red jersey, Australian O'Connor, who now holds a slender 43-second lead going into the final week.
Tyrone man Darren Rafferty (EF Education-Easypost) - appearing in his first Grand Tour - was 68th on Sunday, and is 82nd overall.
