The day began with a breakaway of nine riders at around the 17 km (10.6 mi) mark and consisted of the following riders: Jens Voigt (RadioShack–Leopard), Arnold Jeannesson (FDJ.fr), Christophe Riblon (Ag2r–La Mondiale), Andrey Amador (Movistar Team), Sylvain Chavanel (Omega Pharma–Quick-Step), Lars Boom (Belkin Pro Cycling), Tom Danielson (Garmin–Sharp), Tejay van Garderen (BMC Racing Team), and Moreno Moser (Cannondale). By the 35 km (21.7 mi) mark, they had extended their advantage over the peloton to 5' 40".[2] Van Garderen would attack his leading companions at the foot of the first ascent of Alpe d'Huez, with only Moser and Riblon able to keep pace and caught up with him 1 km (0.6 mi) away from the top of the climb. Despite multiple mishaps – van Garderen's chain fell on the descent of the Sarenne and Riblon went off the road – the three leaders were firmly in the lead at the base of the second climb of Alpe d'Huez.[3] Once again, van Garderen attacked at the base of the climb and quickly distanced himself from his leading companions. Riblon, despite being down 40 seconds to van Garderen at one point, would claw his way back up and passed him with 2.4 km (1.5 mi) to go, and ultimately won the only stage by a French rider in the 2013 Tour.[2]
Back in the peloton, major changes were occurring in the general classification. Belkin Pro Cycling riders Bauke Mollema and Laurens ten Dam both cracked at the beginning of the climb and slid a couple of places on the leaderboard. Nairo Quintana (Movistar Team) attacked the group and was followed closely by Team Sky's Chris Froome and Richie Porte as well as Team Katusha's Joaquim Rodríguez. The Saxo–Tinkoff trio of Alberto Contador, Roman Kreuziger, and Michael Rogers were unable to follow and would lose significant amounts of time. With 5 km (3.1 mi) to go, Froome and Porte would lose contact with Quintana and Rodríguez; at which point Porte dropped back to the team car to illegally get energy gels for his leader, then paced him to the end of the climb to limit his losses to Quintana and Rodríguez.[3] Porte and Froome each received a 20-second time penalty and a fine of 200 Swiss francs for the infringement.[4][5]