The breakaway group rides through a tunnel during Stage 7 of the Tour of California cycling race on Saturday, May 21, 2011, in Los Angeles County, Calif. (AP Photo/Mark J. Terrill)

SANTA ROSA, CALIFORNIA, May 11 (Reuters) – The Tour of California, the most prestigious annual cycling race in the United States, gets underway on Sunday.

A stellar field of 128 elite riders, including eight UCI ProTour teams, have entered the eight-day event that covers more than 735 miles (1,184 kilometres) through the jagged mountains and spectacular coastlines of the Golden State.

Even though the race clashes with the Giro d’Italia, interest has been heightened both because of changes to the course, including a stage that will start in Beverly Hills, and because it comes just before the Tour de France and the London Olympics.

In five of the previous six editions of the Tour, the overall winner has been an American, and the host-nation has a strong hand again this year.

Last year’s winner Chris Horner is again looming as the man to beat although he faces some stiff opposition from his countryman Levi Leipheimer, a three-time winner in California, and Belgium’s Tom Boonen, the number one ranked road cyclist in the world.

Horner, 40, has been plagued by injuries and bad luck since last year’s victory. He is still recovering from a cold but expects to be at his best when the Tour begins in Santa Rosa.

“Things are looking pretty good for California,” said Horner.

“It’s less ideal for me than last year, but will be harder for most of the field because of the additional climbing in the early stages.”

Leipheimer is still recovering from a broken leg he suffered when hit by a car while training in Spain and remains in some doubt for the race.

That opens up the prospects for a European winner. Leipheimer’s teammate Boonen has already won the Paris-Roubaix and Tour of Flanders this season while Italy’s Vincenzo Nibali won the 2010 Tour of Spain.

The sprint stages look set to be fiercely contested between

Peter Sagan of Slovakia, Marcus Kittel of Germany and Australian Robbie McEwen.

The tour ends on May 20 with the final stage that starts on Rodeo Drive and ends in downtown Los Angeles.