Cavendish leads the Tour's points competition
Mark Cavendish finished half an hour behind Ezequiel Mosquera in the Tour of Spain's penultimate stage, but remains favourite to win the points title.
Cavendish, who has won three stages on the tour, maintained a 12-point lead over United States rider Tyler Farrar.
In the overall standings Vincenzo Nibali remains on course for victory.
The Italian was one second behind Spain's Mosquera on Saturday but retains a 41- second advantage going into the short final stage.
Prior to Saturday's stage, Nibali had admitted that the battle against Mosquera in the Guadarrama mountains would prove decisive ahead of the final stage through Madrid.
And the Italian clung desperately to his rival's wheel up the 2,247-metre Bola del Mundo ascent, finishing only a second behind his rival after the 172.1km ride from San Martin de Valdeiglesias.
Peter Velits, third in the overall standings, finished eighth in the 20th stage, 52 seconds back, to retain his position.
The final stage is an 81km route from the suburbs into the Spanish capital, offering few opportunities to attack. Certainly Mosquera believes Nibali will be crowned champion.
"I pushed myself to the limit thinking that I could win the stage, dreaming of winning the Tour, when I saw that Nibali had caught up I thought it was all lost," he said.
"But I'm proud of being behind a great champion like Vincenzo Nibali."
Nibali, meanwhile, felt victory would elevate him to the ranks of "great" riders.
"When you win [a Grand Tour] it's an honour, especially against a rival like Mosquera who deserved to win," said the 25-year-old.
"It's an important victory. I will join the group of 'great riders' and it's something I had dreamed of since I was very young."
Cavendish finished in a group 30 minutes back from the leaders, failing to pick up any points, but his rivals, notably Farrar, failed to make significant inroads into his lead.