Spain's Antonio Piedra won the Sunday's 15th stage of the Tour of Spain after he launched an attack during the final climb of the race while Joaquim Rodriguez kept the overall race lead.

It was the biggest win of 26-year-old Caja Rural rider's career and it is the first time that the team has won a stage at the Tour of Spain.

Piedra, part of a group of 10 riders who broke away from the rest of the peloton right at the start of the race, crossed the mountain top finish line far ahead of his nearest rival, fellow Spaniard Ruben Perez Moreno.

He pulled ahead of the rest of the breakaway group with about 10 kilometres left in the 186.5 kilometre ride from La Robla to Lagos de Covadonga in the rugged, northern region of Asturias and his rivals could not catch up.

‘Incredible’ win

Piedra completed the stage in five hours, one minute and 23 seconds, two minutes and two seconds head of Euskaltel's Moreno.

"It is incredible. This will be something I will remember for the rest of my life," he said at the end of the race.

France's Lloyd Mondory finished the stage in third place.

Rodriguez held on to the overall leader's red jersey as well as his 22-second lead over Spain's Alberto Contador, who is in second place.

Another Spaniard, Alejandro Valverde, is in third place in the overall standings, 1:41 behind the leader.

Britain's Christopher Froome of Team Sky lost more ground on Sunday, slipping to fourth place in the overall standings, 2:16 off the leader.

"Joaquim is in the strongest shape of his life," said Contador at the end of the race.

"I was not feeling very well today so I preferred to keep my energy for the final mountain stage."

Britain's Christopher Froome of Team Sky lost more ground on Sunday, slipping to fourth place in the overall standings, two minutes and 16 seconds from the leader.

Monday sees the peloton head into a third straight mountain stage - a 183.5-kilometre ride from Gijon to Valgrande-Pajares that features inclinations of 24 per cent during the final three kilometres. Tuesday is a rest day.

The 21-stage Tour of Spain - one of cycling's three 'major tours' along with the Tour de France and the Giro d'Italia - finishes on September 9 in Madrid.

Source: AFP