Alexandre Vinokourov has given up any hopes of winning the Tour de France later this year and will concentrate on helping team mate Alberto Contador to a third title, the Astana rider said.

The 36-year-old, who served a two year suspension for blood doping, is a surprise leader of the Giro d'Italia heading into Wednesday's fourth stage, a 33-kilometre team time trial, and his goal was to win the Italian crown before aiding Contador in July.

"In the past everything was for victory as team leader at the Tour," he told Reuters in a telephone interview from his hotel near Savigliano, Italy. "This year I have a different goal.

"I came to the Giro in my peak form, so the Giro is number one for me, and at the Tour de France my goal will be to help Contador win, so I will ride the Giro, take a break, then ride the Tour."

Vinokourov, who denied any wrongdoing when he tested positive for blood doping in the 2007 Tour de France and was suspended for two years, added while being back in the sport had reinvigorated him he was aware his career was winding down.

"I hope to stay in professional cycling, because I've spent most of my life in bike racing, and I'd like to stay doing my favourite thing," he said when asked of any future plans.

"That will all be seen either in this year or in the next one, how I do in the races. I'll make a decision after the Tour de France."

Vinokourov made a low-key return last year when his suspension ended and has won two major races already this year, at Italy's Giro del Trentino and then the Liege-Bastogne-Liege race in Belgium, where he was booed by spectators and grilled heavily by the media.

Despite his earlier success, the ethnic Russian from the tiny farm village of Beshikul in northern Kazakhstan, was still surprised that he was in such strong form in Italy.

"I didn't expect the pink jersey," he said in reference to taking a surprise lead on Monday after a windswept third stage in the Netherlands knocked dozens of riders to the ground.

"To wear the pink jersey at my first Giro, it's more than I could have dreamed."

"If we hold on to it remains to be seen, because it's still a long way to (the end of the race in) Verona and I don't want to kill the team."

"The last week will be really hard, and so it's better for the team to preserve it's strength."