Four-time defending AMA Supercross Champion Ryan Villopoto is leaving the United States and taking his talents overseas to the Motocross World Championship series.

The move announced today by Kawasaki along with the launch of the company's Ninja H2 sportbike comes as no surprise. It was widely speculated that Villopoto would challenge the best on the world's stage though many thought, and fans hoped, he might try and race for an unprecedented fifth-straight Supercross Championship. On his website, Villopoto posted "The Road Back Up" in the "News" section, dated today, giving an overview of his time-off activities and ending with "Big stuff is acomin!"

Villopoto made winning look pretty easy in recent years taking the last three Supercross Championships and the 2013 AMA Motocross championship with at least one race remaining in the season. Very few riders actually competed against the Washington-state resident and those that did fell so far behind just a few rounds after mid-season, the remaining races seemed all but a formality.

In the MXGPs, Villopoto's primary competition lies with Antonio Cairolo of Italy. Cairolo won his eighth World title earlier this month - also a round early. The two riders pit against each other very well and the anticipation of the 2015 match-up has been brewing for some time. Villopoto takes nine AMA 250 and 450 titles against Cairolo's eight MXGP titles. Villopoto has 73 victories to Cairolo's 72.

The only time Villopoto and Cairolo raced against each other came in the 2006 Motocross of Nations. In Moto 1 for MX1 and MX2 bikes, Villopoto took third to Cairolo's 10th place but in Moto 2, for MX2 and MX 3 bikes, both riders battled for the checkered flag with Cairolo taking the victory. Overall, Villopoto took the class win and team victory.

Cairolo crashed out in this year's Motocross of Nations in Latvia while Villopoto, who missed the 2014 Motocross season, stayed home and rested a surgically repaired knee. A dark horse in the Villopoto vs. Cairolo matchup is Gautier Paulin who propelled France to a dominating 2014 MXoN victory. Paulin went 1-1 in the MXGP class.

Bobby Moore was the last American to win a Motocross World Championship which he did in 1994 in the 125cc class. Mike Brown took third in 1999 and 2000 in the same class. No American has placed in the Top 3 since the format changed to the MX1, MX2 and MX3 class in 2004. Neither Ricky Carmichael nor Jeremy McGrath raced in the MXGPs. Villopoto can certainly stamp his name near the top, and many might argue at the top, of the echelon of the all-time greatest Motocross and Supercross racers if he can bring home an MXGP Championship.

Villopoto's pending absence in the 2015 Supercross and Motocross seasons certainly adds some intrigue for fans stateside but will shine a spotlight on the little followed MXGPs in the US. Though Villopoto die-hards are likely disappointed their hero won't compete for a fifth-straight Supercross title, those riding in the field now have a realistic shot at a Championship as there's little reason to believe a healthy Villopoto wouldn't again ride off with more #1 plates next year.

Update: Kawasaki issued an official statement Tuesday verifying Ryan Villopoto racing in the 2015 Motocross World Championship series in the MXGP class. Villopoto also indicated this is the final chapter of his career saying:

"I am ready for the next chapter in my career and to accomplish new goals. I've never been one to look at the record books so when an opportunity like this comes around, to race against the best in the world and represent USA, I have to see it through. It will be a major change of pace and this will be the last chapter of my career win or lose. I am extremely excited about the opportunity and also to be joined by a former champion like Tyla (Rattray). He knows what is needed to succeed on the world championship stage and I know I can learn a lot from him."