Vuelta a Burgos
In 2006, he won stages at the Tour de Romandie and Tour de Suisse in preparation for the Tour de France. Prior to the start of the race he was implicated along with several teammates in the Operación Puerto doping case by the Spanish authorities, and the team was not able to start. He was later cleared by the Union Cycliste Internationale, cycling's governing body. Contador returned to racing in the Vuelta a Burgos but he crashed after finishing fifth in stage 4, when he was riding back down to the team bus, and briefly lost consciousness.