The race included three categorized climbs, including a finish at the base of the Mount Baldy ski lifts, an ascension that would take the riders to an altitude of . Right from the start, a breakaway formed, initiated by Jens Voigt (RadioShack-Nissan) and Dries Devenyns (Omega Pharma-Quick-Step). After of racing, the break had ballooned to 14 riders, including four units from the RadioShack-Nissan squad. Back in the group, general classification contender Tejay van Garderen of BMC Racing Team survived a scare when he punctured while descending the first categorized difficulty of the day, but a teammate was there to promptly give him his wheel. Chris Horner (RadioShack-Nissan), who was part of the break, left the escapees behind, accompanied by Darwin Atapuma of Colombia-Coldeportes. At one point, the duo enjoyed a 3' 50 advantage over the bunch and David Zabriskie, making Horner the virtual leader. On the slopes of Mount Baldy, with to go, the chasing bunch was reduced to 15 riders including Zabriskie. Rabobank's Robert Gesink then accelerated toward the top of the climb, dropping everyone in his group except Tom Danielson (Garmin-Sharp) who was the last to go away. Gesink caught Atapuma near the final kilometer banner, was passed by the Colombian on the inside in the penultimate turn, passed him again but took the final left bend very wide, almost colliding with the barriers. Gesink produced a last sprint that would carry him over the line as the victor. With that victory, Gesink took the yellow jersey. He stated: This is amazing. At the end of last year I crashed and broke my leg. In January I still had to learn how to walk. Now I'm back. I've been working really, really hard the last few months.