Lance Armstrong retained his overall lead in the Tour de France's flat, fast stage 13 on Friday, won by Robbie McEwen in a sprint.

The win was McEwen's third of this year's Tour. Armstrong and his main rivals finished together in the stage across southern France before the race heads into the Pyrenees on Saturday.

Armstrong's lead over second-place Mickael Rasmussen of Denmark stayed at 38 seconds, with French rider Christophe Moreau still third, 2 minutes 34 seconds behind the six-time champion.

Italy's Ivan Basso remains 2:40 back, fourth overall. Jan Ullrich of Germany is 4:02 behind but rose to eighth in the standings after Spain's Alejandro Valverde retired with an injury. Valverde, winner of the first Alpine stage, had been fifth overall.

"Everybody is waiting" for the Pyrenees, said Armstrong, explaining why he and his rivals did not battle over Friday's 107.8-mile trek from Miramas to Montpellier.

Ullrich was 25th, Armstrong 33rd, Rasmussen 57th and Basso 72nd. They and McEwen all finished with the same time of 3:43:14.

The first of the three Pyrenean stages has five progressively harder climbs before finishing with a steep ascent to Ax-3 Domaines.

Armstrong, looking gaunt and exhausted, placed fourth the last time the Tour visited the ski station in 2003 -- the shakiest of his record six wins. Ullrich powered past Armstrong on the climb, cutting the American's overall lead to just 15 seconds. Spain's Carlos Sastre won the stage that day.

Armstrong has been stronger so far this year.

The Ax-3 Domaines climb rates a 1 on the rising scale of difficulty that starts at 4.

Before that final ascent comes the 9.4-mile climb over the Port de Pailheres. It peaks at 6,565 feet and is so hard that it is classified as "hors categorie" -- or unrated.

Saturday's 137-mile stage from Agde on the Mediterranean coast is followed Sunday by perhaps the hardest stage this year. It has a succession of five climbs, one rated 2, the others 1, before an "hors categorie" final ascent to Saint-Lary Soulan.

Monday is a rest day before the last high mountain stage. Should the Pyrenees not prove decisive, the outcome of the three-week race will likely be decided in a time trial the day before the Tour ends July 24.