Fabian Cancellara has won the 2010 Tour of Switzerland prologue, while Lance Armstrong finished far back at the start of his last stage race before the 2010 Tour de France - in rainy conditions.

The Swiss clocked 10 minutes, 21 seconds in the 4.7-mile time trial in and around the lakeside town of Lugano.

Czech rider Roman Kreuziger was second, 1 second behind, and Tony Martin of Germany was third, 3 seconds behind Cancellara. Armstrong was 44th overall, 29 seconds back.

Cancellara, the time trial world champion, has been at the center of speculation that some riders may be cheating by using tiny motors hidden in their bike frames. He denies he won the Paris-Roubaix and Tour of Flanders this year with help of an electric bike.