By Julien Pretot FLORENCE, Italy (Reuters) - Once again, Fabian Cancellara will start a one-day race with a big target on his back in Sunday's elite race at the world cycling championships. Cancellara's sheer power, combined with his ability on tough, short climbs, make him the clear favorite for the 272.3-km trek from Lucca to Florence. After 106.6 kilometers on the flat, the peloton will go around a 16.6-km circuit which includes the Fiesole climb (4.4 km with a gradient of 5.2 percent) and the Via Salviati (600 meters at 10.2 percent), where the pure sprinters will be eliminated. ... More...