On which stage did Fabian Cancellara win the yellow jersey in the Tour in 2009?

Explanation

The Swiss cyclist Fabian Cancellara (born 1981) is a specialist in individual time trials and cobbled streets. In 2009, he won the first stage of Tour de France. It was an individual time trial, covering a distance of 15.5 km. Team Saxo Bank defended the yellow jersey until the 7th stage, which was the first mountain stage on that year's tour. He lost the jersey to Rinaldo Nocentini, who wore it until Alberto Contador set things right on the 15th stage.