Tour de France leader Alberto Contador and second-place teammate Lance Armstrong have started on the 16th stage of the race, which goes into the Swiss Alps.
The pack is heading on a 98.8-mile ride from Martigny to Bourg-Saint-Maurice, France, via Italy and up the Grand-Saint-Bernard and Petit-Saint-Bernard passes.
Tuesday's stage follows the second and final rest day in the three-week race. Contador, the 2007 Tour champion, stamped his dominance on the race Sunday by winning the first stage in the Alps. Seven-time champion Armstrong is 1 minute, 37 seconds behind his Astana teammate.
The Tour finishes on July 26 in Paris.