LONDON, July 7 (Reuters) - Swiss Fabian Cancellara of the CSC team won the 7.9-km prologue of the Tour de France on the streets of London on Saturday. Cancellara, already a winner of the Tour's opening time trial in 2004, coped perfectly with the flat course starting at Trafalgar Square and finishing in The Mall to set the best time of eight minutes 50 seconds, according to provisional results. The 26-year-old Swiss will be the first to wear the yellow jersey after beating German Andreas Kloeden of the Astana team by 13 seconds. American George Hincapie of the Discovery Channel came home third. Two years to the day after 52 London commuters were killed in attacks on three underground trains and a bus, 5,000 police officers were deployed along the course which passed Hyde Park, Westminster and Buckingham Palace.