The 23-year-old Slovak, a four-time stage winner in the Tour de France who rides the Italy-based Cannondale team, completed the 60.6-mile, three-lap circuit in 2 hours and 26 minutes.

"I was the people's favorite, yes," said Sagan, who has trained in Colorado for two weeks after winning the points jersey for the second time in last month's Tour de France. "But I was very surprised. The team went to the front for most of the race. I ride tempo."

Greg Van Avermaet (BMC Racing Team) of Belgium finished second and Kiel Reijnan (UnitedHealthcare) of the United States was third in the same time as Sagan.

Commenting on his 2nd place finish, Van Avermaet told Roadcycling.com "I came through the last corner in second position and directly started my sprint because I didn't know where Peter (Sagan) was. In the last 150 meters, he came over me. But it was good to try it. I know Peter is a little bit stronger than me in the sprint. Second is a little bit disappointing after all of my second-place finishes in the Tour of Utah, but it was good to try."

Sagan, a pre-stage favorite, secured his 16th stage win this season and the 54th of his five-year pro career.

Since the race does not feature any bonus times, Sagan, Van Avermaet and Reijnan have the same overall time, but Sagan is the overall leader based on his stage win.

Sagan was in third approaching the final corner with about 250 yards left. He moved to the right and into the lead within the final 200 yards and was never challenged.

Chris Froome (Team Sky) of Great Britain, the reigning Tour de France champion, struggled on the final climb and finished 77th -- nearly 5 minutes behind Sagan.

Defending champion Christian Van de Velde (Garmin-Sharp) of the United States placed 24th in the opening stage and was credited with the same time as Sagan.

"I felt very good," said Sagan. "It was only 100 kilometers today and tomorrow will be harder. But I am happy for today. It was hard, but the climbs were not that long."

Americans Craig Lewis (Champion System), Matt Cooke (Jamis-Hagen Berman) and Ian Burnett (Jelly Belly) escaped from the field after the opening five miles and built more than a 2½-minute lead after the first of three 20-mile circuits.

The trio rode at the front for more than 2 hours on the circuit that included more than 3,000 feet of climbing and encompassed Aspen, Snowmass Village and Woody Creek.

Shortly after the start of the final loop, the leaders' advantage had dropped to 1 minute, 10 seconds.

Lewis and Cooke remained at the front with nine miles left in the stage and lead by 30 seconds. Cooke then surged to the front alone two miles later and built a slight margin before being caught by six riders with slightly more than five miles left.

George Bennett (Team RadioShack) of New Zealand and American Carter Jones (Bissell) jumped to the front and built a 20-second lead with two miles left. But the twosome was caught within a mile from the finish.

The seven-day event continues Tuesday with the 126.1-mile trek from Aspen to Breckenridge. The stage includes three climbs, including the ascent over Independence Pass -- an elevation of 12,095 feet -- about 20 miles into the stage.

The event's third edition continues through Sunday.