Alberto Contador avoided any costly setbacks on the penultimate stage to all but assure himself of the Vuelta a Espana title, with the day's victory going to Denis Menchov.
Contador started the 20th stage with a one minute and 35 seconds lead at the top of the classification, and although his nearest challenger Alejandro Valverde (Movistar) cut the gap by 19 seconds, the Team Saxo Bank rider still boasts a significant advantage heading into the last day, which should see him claim victory.
The 29-year-old Contador is riding in his first grand tour since returning from a drug ban.
Menchov (Katusha) took the honours in today's testing 170.7-kilometre ride from La Faisanera to the mountain-top finish at Bola del Mundo after charging away in the final climb to win in a time of four hours 48 minutes and 48 seconds.
The Russian, who won the Vuelta in 2005 and 2007, finished 17 seconds clear of Australian Richie Porte (Team Sky), with third place going to Belgian Kevin De Weert of Omega Pharma-Quickstep, who was 42 seconds back.
Away from the battle for the stage win, the fight for the overall crown saw Valverde and third-placed Joaquin Rodriguez both close the gap on Contador, but not significantly enough to challenge their fellow Spaniard for top spot.
Rodriguez launched an attack in the final four kilometres to finish ninth today, three minutes and 31 seconds behind Menchov, while Valverde was 10th a further 25 seconds back.
Valverde dropped Contador in the closing stages as he raced after Rodriguez in a bid to avoid losing second place in the overall classification, which he managed to do.
Heading into tomorrow's 115km final stage from Cercedilla to Madrid, Contador is one minute 16 seconds clear of Valverde as he prepares to claim his second Vuelta title, with Rodriguez one minute 37 seconds adrift.
Briton Chris Froome of Team Sky is fourth, more than 10 minutes behind Contador.
Ireland's Nicolas Roche finished 27th, 5:35 behind Menchov. He is 12th overall, 17:50 off the lead.