Thor Hushovd of Norway led a mass sprint finish Thursday to win the sixth stage of the Tour de France along rain-slickened roads south of the French border in Spain.

Fabian Cancellara of Switzerland kept the yellow jersey, with just a split-second lead over Lance Armstrong after the 181.5-kilometre course from Gerona to Barcelona.

Hushovd, of the Cervelo Test Team that is principally owned by the Canadian bike manufacturer, collected his seventh Tour stage win by edging out two Spaniards — three-time world champion Oscar Freire in second, and Jose Joaquin Rojas in third — in the final sprint.

"I'm just too, too happy," said Hushovd, who won the best sprinter's jersey at the 2005 Tour. "It's true that it was a nervous day too, because it was raining and the roads were slippery."

They clocked four hours, 21 minutes, 33 seconds for the stage, the same time as 40 other riders including seven-time Tour champion Armstrong and Cancellara in the main pack of favourites.

Breakaway riders including Britain's David Millar repeatedly attacked, only to be reeled in by the finish. He was caught with little more than one kilometre left to go.

The three-week race enters a new phase on Friday with the first big mountains in the seventh stage.

"Tomorrow is an important day," Armstrong said. "I don't know if it's the most important day, but it's definitely a big appointment on this Tour."

The 224-kilometre ride from Barcelona to Arcalis, Andorra, features five ascents including the Category 1 Serra Seca pass, and an uphill finish on one of cycling's toughest climbs.

Alberto Contador, the 2007 Tour champion and perhaps the top pre-race favourite, has said he's eager to get to the mountains — and he could make his move then.

Cancellara has been the only man to wear the yellow jersey this year. Armstrong is only milliseconds behind, while Contador is third, 19 seconds back.

The Swiss rider isn't expected to fare as well as Contador, Armstrong and other strong climbers in the mountains. Cancellara seemed a bit resigned to the prospect he might now lose the lead.

"What do I have to do tomorrow? It's a good question," he said. "It's been a beautiful week to be in this yellow jersey... I'm going to try to defend it but I don't know how well I can do."

Other strong climbers and potential title contenders who have been distanced on the flat include 2008 Tour winner Carlos Sastre, two-time runner-up Cadel Evans, and brothers Andy and Frank Schleck.

"Tomorrow is a very long stage and it could suit him well," Contador said of Sastre on Spain's TVE television. "If I see a situation that is favourable to me, and if my legs respond, then I'm going to try and go for it."

Armstrong seemed to be bracing for as much from Contador.

"I know Alberto wants to assert himself in the race. I don't need a team meeting to know that," the 37-year-old Texan said.

"If he goes and nobody can hang with him, I'll just stay with the other leaders," he added. "But I'll show up tomorrow morning, try to do my best, get to the top as quick as I can, and we'll see."

The Tour ends July 26 in Paris.