Estonia's Jaan Kirsipuu won a mass sprint finish to claim the sixth stage of the Tour de France on Friday.

Race leader Stuart O'Grady finished in the main bunch to keep the yellow jersey for the fourth successive day.

Kirsipuu, riding for the AG2R team, completed the 211.5km stage from Commercy to Strasbourg in four hours, 50 minutes and 39 seconds.

It was the second Tour de France stage win of his career.

French rider Damien Nazon was second and Jan Svorada of the Czech Republic was third, both recording the same time as Kirsipuu.

Erik Zabel of Germany wobbled and raised his hand in the final metres, possibly signalling a foul.

He had been riding close to Nazon at the time, but it was not immediately clear why Zabel, who finished fifth, made the gesture.

Defending champion Lance Armstrong bounced back from a disappointing team time trial on Thursday to finish in the same time as Kirsipuu.

He crossed the line in 48th place and stays 27 seconds ahead of arch rival Jan Ullrich in the overall standings.

Mountain woes

The stage took the riders over their first mountain pass, the Col du Donon.

At one point a breakaway that included Axel Merckx and Laurent Brochard led by three minutes.

The group was clear for more than 150kms but was caught before the finish, setting the scene for the flying Kirsipuu to take the stage.

Afterwards, the stage winner was quick to praise the endeavours of his team-mates.

"The sprints for the first few days were crazy and Erik Zabel [who won two of them] was lucky," he said.

"They were just a lottery, with no tactics.

"This time, with 500 metres to go, Ludovic Capelle touched me on the behind and told me to go - I hadn't seen him in the race before then.

"My team-mates encouraged me to go for it."

Kirsipuu knows that tougher times lie ahead, however.

Aware of his limited mountain climbing ability, he is preparing for "days and days of suffering" on the slopes.

Saturday's stage is a 162.5km ride from Strasbourg to Colmar.