AX-3 DOMAINES, France - His legs weary and his lead shrinking, Lance Armstrong has never been in a Tour de France like this.

The four-time champion can no longer count on a triumphant march through Paris. Instead, his lead Saturday was cut to 15 seconds over a surging Jan Ullrich, who seems ready to seize the yellow jersey.

''It's never been, obviously, this close,'' Armstrong said. ''It's a different race, perhaps more exciting.''

Ullrich, looking almost fresh while Armstrong looked haggard, powered past the Texan on the final punishing climb in the first of four critical stages in the Pyrenees. The German gained 19 seconds on Armstrong.

''This was a very difficult effort,'' said Armstrong, who was fourth in the 13th stage.

Never has the Tour been this tight at this point since Armstrong first won in 1999. Ullrich, the 1997 winner, was second in the stage and is intent on more.

''I'm going to try to take the yellow jersey tomorrow,'' he said through a translator on French TV. ''I'll see how I feel, and if all goes well, I'll do the maximum.''

Spain's Carlos Sastre won the 122.5-mile race from Toulouse to the ski resort of Ax-3 Domaines. The ride featured a 9.4-mile climb over a pass called Port de Pailheres, towering at 6,603 feet above sea level.

Sastre, of the CSC team, stuck a baby's pacifier in his mouth as he finished in tribute to daughter Claudia, who turns 2 next month.

Ullrich was 61 seconds behind Sastre, who was timed in 5 hours, 16 minutes, 8 seconds. Spain's Haimar Zubeldia was third, 1:03 behind. Armstrong was next, 1:08 back.

Ullrich's runner-up finish in the stage resulted in a bonus of 12 seconds in the overall standings.

He drew away from Armstrong in the last 5.6-mile climb. They raced shoulder to shoulder and looked at each other before the German sped ahead.

Ullrich dropped Armstrong and overtook Alexandre Vinokourov. Ullrich roared to the line grimacing, but he did not look as drawn as Armstrong.

There was some good news for Armstrong - he gained 10 seconds on Vinokourov. The Kazak finished fifth, falling 61 seconds behind Armstrong overall.

''I'm not very disappointed,'' Armstrong said.

But he added that Ullrich ''looks to be riding great, better and better every day.''

''I'm just going to ride my rhythm and not let him get too far,'' Armstrong added.

Weakened by the persistent heat, Armstrong was depleted from Friday's time trial in which Ullrich prevailed. He had doubts about his ability to dominate Saturday.

''I didn't expect to have super legs - yesterday was too hard. It was a really difficult effort,'' Armstrong said. ''To recuperate … is not possible in 24 hours, or 20 hours.''

''At the start … I thought, 'Uh-oh' it's going to be a bad day, but there are two more days left in the Pyrenees, and I still have a lot of chances,'' he said.

Ullrich appears at the top of his game. He was 96 seconds ahead of Armstrong in the time trial, setting up tense days of racing in the rugged mountains separating Spain and France.

Armstrong is trying to equal Spanish rider Miguel Indurain's record of five consecutive Tour wins. His chance to stamp his authority on the three-week race could come Sunday when forecasts of rain in the Pyrenees may provide some cool.

Now, with seven days of racing to go, Armstrong has to adjust his strategy.

At ''other years at this point, no, I was lucky enough to have three or four or five minutes'' advantage over competitors, he said.

Armstrong knows he must build a bigger cushion over Ullrich before a final time trial July 26, the day before the Tour finishes in Paris.

''One of the two will crack,'' French rider Richard Virenque predicted. ''There's going to be destruction in the days to come. It's going to be spectacular.''