SEGOVIA, Spain -- Alberto Contador lost 17 seconds of his overall lead Friday with only one more day of real racing left in the Spanish Vuelta.
The Spaniard, bidding for his second Vuelta title, leads Alejandro Valverde by 1:35. Joaquin Rodriguez is 2:21 behind in third before the mountain stage on Saturday.
Philippe Gilbert of Belgium won the 19th stage ahead of Valverde, who shaved valuable seconds off Contador's lead before the deciding next-to-last leg.
Gilbert held off the Spanish trio of Valverde, Daniel Moreno and Rodriguez on the slight climb to the finish line to take the 111-mile stage in 4 hours, 56 minutes, 25 seconds. Contador crossed the line 3 seconds later in 10th place.
The mountain stage Saturday is a punishing 106-mile ride that features five climbs including the special category finish at Bola del Mundo at 7,372-feet.
"Tomorrow's stage is very tough and very threatening," said SaxoBank's Contador, who is on the verge of a fifth victory in cycling's major events after returning from a two-year doping ban. "All the elements are there to make it memorable."
The 21-stage Spanish classic ends Sunday in Madrid, with a straightforward stage that is merely a precession. Valverde, the 2009 winner, will need an impressive performance to capture his second Vuelta.
"Everything can stay the same, or the podium could swap around -- it could be a crazy day," Valverde said. "But with Alberto leading, it's tough to imagine improving the position."