That ends tonight.

Stewart will race on Yamaha blue for the first time when the U.S. Open begins a two-night run at the MGM Grand Garden with the top riders gunning for a potential $250,000 payday, which includes a guaranteed $100,000 for best combined finishes over the two nights.

"It's a big change but a great change," he said Oct. 3 in a telephone interview moments after announcing his switch from the Kawasaki factory team to the independent L&M San Manuel Yamaha team.

"I'll have to get rid of my green stuff, but I still like green as a color," he said with the laugh that has endeared him to fans. "And some green is still coming in."

That "green" reference was to money. Although he has not revealed the value of his two-year deal with Yamaha, it's probably the circuit's richest.

"It will be a challenge getting used to (the team bike and team) in just a few days," said Stewart, who has been the fastest in Supercross the past few years but has battled durability more than the competition.

Stewart, 22, won the 2006 Supercross title but was injured during the AMA Outdoor motocross season and missed last year's Open. After reinjuring his left knee in December, he decided to have it surgically repaired, which kept him out of this year's Supercross season.

"One year I win the Open, then next year I can't race," he said. "I could never finish an outdoor season the past couple years."

That changed this year when he won all 24 motos to claim his first Outdoor title.

"To be able to dominate was very special," Stewart said. "The hard work paid off."

He credits that to Aldon Baker, a sports trainer who worked with former Supercross and motocross champion Ricky Carmichael for several years. Baker was credited with helping to build Carmichael's strength and endurance. He has been doing that with Stewart this year.

"The biggest thing has been going to races knowing I was 100 percent prepared," Stewart said. "I understand why Ricky was so hard to beat; he had a tremendous training program."

Saturday was the first day he rode his 450cc Yamaha on a Southern California test track, and he planned to spend the next few days adjusting to the bike and team.

Stewart replaces Chad Reed, who left to join the Suzuki factory team. The MGM sports book is giving Stewart a slight edge to win the Open over Reed, who won last year's Supercross championship and is a two-time winner of the Open, in 2003 and '04.

A healthy and strong Stewart might not be what his competition wants to see.

"People have called me the fastest guy in the world, and now I'm the also the most in-shape guy in the world," he said. "I'm in the best shape of my life."

The only good news for his Outdoor competition is he will not compete in many motocross races after the Supercross season ends in May.

He might partake in the X Games or use the off time to practice for the Rolex 24 Hours sports-car race in January at Daytona International Speedway, about 90 miles from his home in Haines City, Fla.

"It's something I'm looking at," he said of car racing.

That switch also could be a green one, as in the color of money.

Contact reporter Jeff Wolf at jwolf@ reviewjournal.com or 702-383-0247.