Lance Armstrong and Alberto Contador finish together

Lance Armstrong mustered one of his strongest showings yet at this Tour de France on Tuesday, a dazzling burst of acceleration that allowed him to keep second place.

The seven-time champion was so buoyed by the performance that he suggested he could still contend for the yellow jersey if teammate and race leader Alberto Contador has a “bad day.”

Armstrong, speaking after the 16th stage, stressed he doesn’t expect that to happen and only a “big shake-up” would allow such a scenario.

Contador, the 2007 winner, had to fight to retain the overall lead in the 99-mile Alpine stage from Martigny, Switzerland, to Bourg-Saint-Maurice, France, which was won by Mikel Astarloza of Spain.

As Contador tried to keep pace with two attackers on the final climb, Armstrong lagged. But after dropping back at least 35 seconds, he popped out of his saddle and recovered lost ground.

Contador and Armstrong finished in a small group of race leaders behind Astarloza. Astarloza, who rides for the Euskadi Euskaltel team, thrust his fists in the air and kissed his fingers as he crossed the line in 4 hours 14 minutes 20 seconds. He was six seconds ahead of French riders Sandy Casar and Pierrick Fedrigo.

The course ended with a 19-mile downhill run, and the final descent was perilous: Jens Voigt of Germany crashed either from a bicycle malfunction or a bump in the road. The Tour’s medical staff said he severely bruised his face and right elbow and was flown by helicopter to a hospital in the French city of Grenoble.

Quote of the day: “It’s easy to explain -- he’s a very great rider. He was in the past, and he showed it once again.” -- Contador, on his Astana teammate Armstrong.

STAGE 16 RESULTS

1. Mikel Astarloza, Spain

4:14:20

2. Sandy Casar, France

:06behind

3. Pierrick Fedrigo, France

same time

4. Nicolas Roche, Ireland

same time

5. Jurgen Van Den Broeck, Belgium

same time

OVERALL STANDINGS

1. Alberto Contador, Spain

67:33:15

2. Lance Armstrong, U.S.

1:37 behind

3. Bradley Wiggins, Britain

1:46 behind

4. Andreas Kloeden, Germany

2:17 behind

5. Andy Schleck, Luxembourg

2:26 behind

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TODAY’S STAGE 17

Today’s stage: The 17th stage is a 105.3-mile ride from Bourg-Saint-Maurice to Le Grand-Bornand, featuring five climbs. The final ascent’s summit is only 9.3 miles away from the finish, and this stage is regarded as the most difficult in the Alps this year.

Destination Le Grand-Bornand: On the western slope of the Aravis Mountains, Le Grand-Bornand is composed of three areas: the Bouchet and Chinaillon valleys with the village of Le Grand-Bornand in between. It was the starting point for the Tour in 1995, 1999 and 2007 and the finishing point in 2004 (a Tour that was won by Lance Armstrong) and 2007. Le Grand-Bornand is a thriving ski resort town. Reblochon cheese was first created there during the 13th century.

-- Lauren Goldman