Joaquim Rodriguez showed his aptitude on the high mountains as he outpaced pre-race favourite and fellow Spaniard Alberto Contador at the end of an arduous stage through the sierras of north-west Spain.

Rodriguez powered ahead of Contador at the end of a 10 kilometre climb to claim his third stage victory of the 2012 race and extend his overall lead to 22 seconds over Contador.

Britain’s Chris Froome remained third overall despite finishing sixth.

Rodriguez stayed calm as Contador’s Saxo Bank squad maintained a high pace over the race’s first four classified climbs, then upped their speed yet further on Ancares’s lower slopes.

Contador shed Froome with four kilometres to go and then went clear of Rodriguez and Alejandro Valverde two kilometres from the line.

However, Rodriguez clawed his way back into contention to zip past Contador and claim the first of three successive high mountain stages.

“It’s a good start to these decisive stages but there’s still some very tough days in the mountains to come and with 90 seconds lead, it can all go wrong very easily,” Rodriguez, who was beaten on the final day of the this year’s Giro d’Italia, told reporters.

“Alberto’s attacks are really dangerous, really spectacular, I suffered like anything to stay on his wheel.

“But I saw that Valverde was closing the gap and I knew I had to go for it again.”

Asked if his performance on Saturday proved that he could succeed on the mountains, he replied: “I don’t know why there have ever been any doubts, somebody out there is obsessed with that idea. Losing to someone like Alberto or Froome on the big climbs is no disgrace.”

Contador, who hugged Rodriguez after crossing the finishing line, added: “I knew that if it came down to the two of us in the last kilometre, Joaquim would win.

“I’ve got three hard days in the mountains left to try and beat him. This isn’t over yet.”