PARIS — Alberto Contador won the Tour de France for a second time today, and Lance Armstrong capped his return to the race with an impressive third-place finish.

Mark Cavendish of Britain collected his sixth stage win of this year's Tour in a sprint after the 101.9-mile course ride from Montereau-Fault-Yonne to the Champs-Elysees.

Over nearly 3,500 kilometers and 21 stages of races over three weeks, Contador repelled many challenges in the mountains, excelled in the two time-trials — winning a pivotal race against the clock in the 18th stage — and won the first Alpine stage.

Contador, the 2007 champion, also had to battle a rearguard action within his Astana team, where the comeback of Armstrong to the Tour after 3½ years of retirement raised questions about who would be the team leader.

Contador began the Tour on July 4 as the pre-race favorite. At only 26 years old, the Spaniard is already one of cycling's greats, having won all three Grand Tours of France, Italy and Spain.

He had to sit out last year because of a doping scandal at Astana that erupted before he joined.

Armstrong, the 37-year-old seven-time Tour champion, is the second-oldest rider to reach the Tour podium. Raymond Poulidor of France was 40 when he placed third in 1976.

Cavendish set his own record by becoming the first rider to win six Tour stages in a sprint. But Thor Hushovd of Norway beat the 24-year-old Briton for the green jersey given to the Tour's best Tour sprinter.

"It's amazing. I'm so happy to be here," Cavendish said. "Six stage victories on the Tour — all my dreams have come true."