Cap’Decouverte, France ? An exhausted Lance Armstrong is the first to admit it: He’s no longer the man to beat in the Tour de France.

Parched and weak after a ride on a scorching day, the four-time champion ran out of energy — and water — on a key stage leading to the Pyrenees.

The Texan finished second in an individual time trial Friday and lost precious time to one of his main rivals — stage winner Jan Ullrich of Germany, who moved into second place overall.

Not since Armstrong overcame cancer to return to the Tour in 1999 has his grip on cycling’s most prestigious race looked so tenuous.

He barely kept the overall lead after a crucial time trial in which riders unleash every bit of force to beat the clock.

Armstrong did extend his overall lead from 21 seconds to 34, but he had been counting heavily on using this stage to distance himself from the field.

Instead, Ullrich is lurking.

Ullrich, a 1997 Tour winner and twice runner-up to Armstrong, powered across the 29 miles of rolling vineyards in 58 minutes, 32 seconds to take the Tour’s 12th stage. He was the only rider of 167 to finish in less than an hour.

Ullrich, of Team Bianchi, shaved more than 11/2 minutes from Armstrong’s lead as the Tour enters the lung-wrenching Pyrenees.

Lance Armstrong strains during the 12th stage of the Tour de France. Armstrong struggled Friday in Cap'Decouverte, France.

“Now he’s the big favorite,” Armstrong said.

Armstrong looked stunned when he ascended the podium to accept the leader’s yellow jersey. Afterward, he seemed spent — physically and emotionally.

“I had an incredible crisis. … I felt like I was pedaling backward,” a flush-faced Armstrong said. Temperatures in the shade reached 97 and were far worse in the sun.

“Perhaps it was too hot for me,” Armstrong said. “I don’t know. I suffered.”

Armstrong lamented running out of water before the final climb to the finish line, set on a rocky outcrop that was once a carbon mine but later turned into a theme park.

“It’s the thirstiest I’ve ever been in a time trial, right from the beginning for some odd reason,” he said.

Ullrich, however, was absolutely buoyant.

“From the start I never thought I could win this time trial,” he said. “I got my old rhythm back … I didn’t expect this (victory) myself.

“I have never beaten Armstrong in a time trial in the Tour before, and I did it now, in my comeback year.”

More bad news for Armstrong: Ullrich tends to grow stronger as the race enters its final eight stages, four of those in the Pyrenees.

Armstrong was not the only exhausted rider. Immediately after crossing the finish line in fifth place, American Tyler Hamilton — competing despite a broken collarbone — stumbled off his bike, lurched forward and vomited.

Since he won his first Tour in 1999, Armstrong has won six of eight individual time trials. Aside from Friday’s race, his only other loss in the time trial came last year.