BARCELONA, Spain — Lance Armstrong remained a split second behind leader Fabian Cancellara on Thursday after a day of treacherous riding in the rain and the mountains looming at the Tour de France.

Thor Hushovd of Norway led a mass sprint finish to capture the sixth stage along wet roads south of the French border in Spain.

Cancellara, of Switzerland, stayed just ahead of the seven-time champion following the 113-mile ride from Gerona to Barcelona.

"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."

Hushovd, of the Cervelo team, collected his seventh Tour stage win by edging two Spaniards in the final sprint — three-time world champion Oscar Freire, the runner-up, followed by Jose Joaquin Rojas.

They finished in 4 hours, 21 minutes, 33 seconds, the same time as 40 other riders, including Armstrong and Cancellara in the main pack.

David Millar of Britain and Americans David Zabriskie and George Hincapie were among the breakaway riders who attacked, only to be reeled in by the pack. Two crashes over the closing sprint marred Friday's race. Millar was either alone in the lead or in the breakaway group for about three-quarters of the stage.

Two crashes marred the six miles — one involving Yukiya Arashiro of Japan, another involving former world champion Tom Boonen of Belgium, one of Hushovd's main rivals.

The three-week race enters its first big mountain challenge today, with a ride into the Pyrenees. The 140-mile trip from Barcelona to Andorra features an uphill finish in one of cycling's toughest climbs. The Tour ends July 26 in Paris.

"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."

Alberto Contador, the 2007 Tour champion, 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 so far. Armstrong is only a fraction of second behind the Swiss rider and Contador is third, 19 seconds back.

Cancellara 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 fallen behind on the flat stretches include 2008 Tour winner Carlos Sastre, two-time runner up Cadel Evans and brothers Andy and Frank Schleck.

"If I see a situation that is favorable to me, and if my legs respond, then I'm going to try and go for it," Contador said on Spanish television.

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."