The fourth annual professional bicycle race made its first appearance in San Diego County with an exhausting 96.8-mile leg from Rancho Bernardo up the 6,140-foot Palomar Mountain and back down to downtown Escondido.
The race attracted tens of thousands of fans who lined roadways, ran along with the bicyclists, dressed in sometimes outlandish costumes and chalked encouraging messages into the pavement.
Leipheimer, 35, entered the final stage wearing the leader's yellow jersey and was never threatened as he rode along with Armstrong in a large pack of racers.
"Lance put his foot down on Cole Grade (Road)," Leipheimer said in a post-race television interview. "It was awesome."
The winner of the individual stage was Frank Schleck of Luxembourg, who completed the course in 3:48:40. Leipheimer was ninth, 39 seconds behind.
Schleck and Vincenzo Nibali of Italy broke away from the field as they climbed a hill on Cole Grade Road and never looked back. Schleck out-sprinted Nibali to take the flag at the end.
The field included Armstrong, the seven-time Tour de France winner, and Murrieta-based Floyd Landis, whose own 2007 win in the Tour de Franc was stripped over allegations of doping.
Leipheimer said the mountain section, with its 11.7-mile climb of more than 4,000 feet and snow-covered hillsides, was hard.
"That was a big climb," said Leipheimer, a Santa Rosa resident. "That was Tour de France caliber."