It’s been the biggest race in North America for the past two years, and the third edition of the 650-mile Amgen Tour of California, held over a north-to-south route from February 17-24, will be no exception.

This year’s Tour of California field includes two-time and reigning world champion Paolo Bettini and his Quick Step teammate Tom Boonen, two-time and reigning world time trial champion Fabian Cancellara (CSC), three-time world champion Oscar Freire (Rabobank) and U.S. national champion and defending Tour of California winner Levi Leipheimer in Astana’s U.S. racing debut.

Tour de France winner Alberto Contador will not race for Astana, but American Chris Horner will return to the Tour of California to race alongside Leipheimer.

In all 133 riders from 17 teams will compete at this year’s Tour of California. Teams appearing for the first time include ProTour squads Astana and Bouygues Telecom as well as domestic teams Rock Racing and Kelly Benefit Strategies-Medifast. The race also marks the debut of the High Road and Bissell Pro Cycling teams, which last year were title-sponsored, respectively, by T-Mobile and Priority Health.

Teams with sponsors backing this year’s event include Health Net, CSC, Jelly Belly, Rock Racing and Bissell.

Other recognizable stars from the European peloton include Bradley Wiggins and George Hincapie (High Road), David Millar and David Zabriskie (Slipstream-Chipotle), Thomas Voeckler (Bouygues Telecom), Fabian Wegmann and Bernhard Kohl (Gerolsteiner), David Cañada and Luciano Pagliarini (Saunier Duval-Scott) and Team CSC’s Stuart O'Grady, Jens Voigt and Bobby Julich.

Perhaps the most recognizable name at the race over the past two years, however, has belonged to the state’s governor, Arnold Schwarzenegger, who has been on hand to present the leader’s jersey to Leipheimer at the previous two editions — in 2006 in San Francisco, and last year in the state capital of Sacramento, where this year’s second stage concludes.

Leipheimer enters the race as a defending champion reeling after Wednesday’s news of Astana’s exclusion from all ASO events in 2008. Twice the winner of the race’s former prologue up to San Francisco’s Coit Tower, Leipheimer has named his days riding into his hometown of Santa Rosa on the first stage as “career highlights.”

“Leading a world-class peloton into your hometown wearing the leader’s jersey was amazing,” Leipheimer said. “That’s a very rare and special thing for a cyclist. Having that honor the last two years are among the most memorable moments of my career. It means a lot to me to have led this prestigious race into my hometown and I’ve seen the impact it’s had on the community.”

This year’s prologue has moved to Stanford University in Palo Alto, and will be held on flat roads that are expected to prove less favorable for the 5-foot-7, 140-pound Leipheimer.

“I’ve done some good flat prologues in the past so I know it’s possible,” Leipheimer said. “You have to go in with the intention of winning it, and that’s exactly how I’m approaching it.”

Horner, who comes to Astana after two years spent at Predictor-Lotto, struggled with knee pain during Astana’s recent training camp in Albuquerque, New Mexico, but told VeloNews earlier this week that he’s been treated with acupuncture and is ready to race. Horner said he would ride for Leipheimer, who he expects to repeat his 2007 dominance.

“Levi was putting out good watts at training camp,” Horner said. “He was the only guy at training camp that didn’t look tired. The whole team will look out for Levi, he’s going good, he’s been healthy, and he’s done all the training to show up with the same form as last year.”

Astana’s biggest competition for overall victory will likely come from Team CSC, which has been second overall at both editions of the Tour of California. In addition to Cancellara, CSC brings a strong squad including new signing Jason McCartney, who was third overall last year riding for Discovery Channel; Julich, who finished third in 2006 and fourth overall last year; O'Grady, the 2007 Paris-Roubaix winner who finished fifth overall last year; Voigt, who last year won a stage and finished second overall; and J.J. Haedo, who has won four Tour of California stages, more than any other rider.

American pro continental team Slipstream-Chipotle also brings a dangerous squad that includes national time trial champions in Millar and Zabriskie, who are both favorites for the prologue. Other than Millar, Slipstream has fielded an all-American squad that includes Christian Vande Velde, Tom Peterson, Danny Pate, Steven Cozza, Tom Danielson, Tyler Farrar and Zabriskie, who finished second overall in 2006 but crashed out of the race last year.

Stage 4, the stunning route down Highway 1 from Seaside to San Luis Obispo, will finish near the hometown of High Road team owner Bob Stapleton. High Road’s GC hopes will fall on Hincapie, a two-time Tour of California stage winner, and Wiggins, the reigning Olympic pursuit gold medalist who is a heavy favorite for the prologue. However High Road also fields perhaps the heaviest sprint squad in the race with 2006 under-23 world champion Gerald Ciolek, who finished second to Bettini in San Luis Obispo last year, as well as star sprinters Mark Cavendish and Edvald Boasson Hagen. Aussie Michael Rogers and Canadian Michael Barry, who have raced the Tour of California in previous years, will not compete.

Leading the seven domestic squads looking to leave an imprint on the race is the Toyota-United squad of last year’s stage 7 winner Ivan Dominguez, which has bolstered its sprint team with the addition of Hilton Clarke and Dominique Rollin.

One of the most anticipated teams to enter the Tour of California is a revamped Rock Racing squad. However, the team has submitted a roster with only five riders, with Freddie Rodriguez and Victor Hugo Peña leading the squad. Tyler Hamilton, Santiago Botero and Oscar Sevilla, all named earlier by team owner Michael Ball to Rock’s California team but implicated in Operación Puerto, will not start. The team may name additional riders before Sunday's start.

Other domestic teams looking to shine include the squads of last year’s first- and second-ranked riders on the NRC, Rory Sutherland (Health Net-Maxxis) and Ben Jacques-Maynes (Bissell).

This year’s eight-day route, which begins with a 2-mile prologue at Stanford University in Palo Alto on February 17 and ends on a circuit around the Rose Bowl in Pasadena on February 24, looks to be more challenging than years past.

The addition of the climb up the 4360-foot Mount Hamilton on stage 3, from Modesto to San Jose, will make for a demanding day that also features the late-stage climb over Sierra Road before a fast descent into the finish in San Jose. Hincapie won the stage into San Jose in 2006, finishing in front of Horner out of a 20-man group; last year Voigt won a three-man bunch sprint ahead of Leipheimer and Horner.

And unlike years past, the final stage is no longer a flat circuit race but a challenging point-to-point that could see the race lead change as riders climb the highest elevation ever reached by the Amgen Tour of California on the towering Mill Creek Summit, at nearly 5000 feet. Descending with an eight-mile run to Angeles Crest Highway, the route begins a fast plunge to the Rose Bowl where the peloton will complete the stage with six 5-mile laps on a demanding circuit around the Rose Bowl.

The addition of several 4000-plus-foot climbs may change the outcome of a race that has twice gone to the winner of the decisive time trial. In 2006 Floyd Landis won a windy time trial in San Jose, while last year Leipheimer won a rolling 15-mile race against the clock in the replica Danish village of Solvang. This year’s time trial will again be held on the fifth stage, on a nearly exact course as last year.

“I know the routes although I haven’t ridden the new additions yet,” Leipheimer said. “Like previous years, the time trial is the most important stage. It’s the stage I’m targeting. I’m hoping to win the race again.”

Also new in 2008 is the inaugural Amgen Tour of California Women's Criterium presented by the Redwood Regional Breast Center, a one-day women’s NRC criterium, to be run on stage 1’s closing circuits in Santa Rosa. The Women's Criterium will consist of a field of 125 riders competing for more than $10,000 in prizes. Set as a category Pro/1/2 race and with a limit of eight riders per team, the Amgen Tour of California Women's Criterium will showcase some of the nation’s top professional women, including 2007 NRC overall individual winner Laura Van Gilder of Cheerwine.

As with years past, VeloNews.com will provide up-to-the-minute updates of all the action from the Tour of California.

Also as in years past, race organizers are asking fans to leave the paint at home, explaining that “residents of local communities do not appreciate the permanent remnants of the race, and it jeopardizes the ability to obtain necessary permits in the future.” Race officials request that fans instead use chalk on the road to encourage and root for their favorite teams and riders.

In cooperation with race organizers, the California Highway Patrol will be restricting motorized traffic on Del Puerto Canyon Road, San Antonio Valley Road, Mt. Hamilton Road and Sierra Road on the morning of the race. Only local residents will be allowed past closures on these roads. After meeting with local residents, these closures have been put in place to lessen any negative impacts of the race on the community. Bicycle and pedestrian traffic will not be restricted until the arrival of the race caravan.