In what's now the most highly anticipated season of the FIM Motocross World Championship, at least for followers in the United States, the 2015 series starts Saturday where a very popular and arguably one of the best-ever American riders begins his retirement tour with a chance to bring the United States an MXGP crown on home turf.

Ryan Villopoto, who left an unprecedented chance to win five straight Supercross titles on the table, will face another great Motocross rider in Antonio Cairoli, the Italian on-board to grab a ninth MXGP Championship. Villopoto's decision to try his talents overseas has put a spotlight on the oft overlooked racing series that's seven months, 18 races long and holds rounds in countries around the world.

The final stop?

Glen Helen Raceway in San Bernardino, CA where if all goes according to plan, Villopoto can clinch the United States first ever title in the MX1 class and first MXGP title since 1994 when Bobby Moore stood tall in the 125cc class. Mike Brown was the last American on the final podium which he did in back-to-back years taking third-place in 1999-00 for the now defunct 125cc class. No American has placed in the Top 3 since the format changed to the MX1, MX2 and MX3 class in 2004.

Motocross fans began drooling over the prospect of a faceoff between Villopoto and Cairoli last year when rumors swirled that Villopoto was leaving American racing for the MXGPs. He seriously pondered retirement as he stayed out of the 2014 Motocross series to heal a surgically repaired knee which bothered him for much of his record-tying fourth straight Supercross championship winning run the same year.

A few months later Cairoli won his eighth World Title. Both riders won their respective Championships a round early because they were so far out in front in points. Villopoto takes nine AMA 250 and 450 titles against Cairoli's eight MXGP titles. Earlier this month, Cairoli added to his resume by winning the MX1 and Elite titles in the Italian Motocross Championship series.

Though all eyes will be on Villopoto and Cairoli, it's not just these two lining up behind the gates. Belgium rider Jeremy van Horebeek took second last year to Cairoli and raced well in the 2014 Motocross of Nations grabbing the holeshot in Moto 3 in route to a second-place finish. Kevin Strijbos, also of Belgium, who won a Moto in last year's MXoN, took third in the 2014 MXGPs.

Don't forget Gautier Paulin of France who is also a serious contender for the MXGP title as he finished eighth in 2014 but was instrumental in bringing his country the 2014 Motocross of Nations Championship winning his two Motos. Finally, Clement Desalle, another Belgium rider, who was fourth last year in the MXGPs, shouldn't be overlooked.

Ryan Villopoto last raced in the 2014 Las Vegas Supercross where he led all 20 laps despite winning the Championship a week earlier

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

In an interview with Monster Energy, Villopoto said American racing is completely different than European racing describing the fans as "insane" but the atmosphere at the races as more relaxed.

"Which is good for me because I was looking for something different," he said.

He described jumping from Supercross to Motocross, run by two different organizations, as a world-pool effect for not only the riders but mechanics and everyone else running the team.

"For me doing that again, I wasn't looking forward to that," he said admitting that after last year it was either retirement or move on and do something else. "I've accomplished way more than I ever thought I would in this sport."

Villopoto said you can't compare American riders with European riders because they don't have a similar racing season. Supercross schedules 17 races over four months with a three week break before the 12-race Motocross series over three months.

"Some people think I have a lot to lose when I go over there. Yes and no. If I do end up losing those are the cards I was dealt. The only way we can compare the two worlds as if they did a Motocross series and a Supercross series," he said. "But I think we'll be able to now have the closest comparison anyone has ever seen or has seen in a very long time."

Villopoto said racing the MXGPs is a big undertaking and likens it to starting over as he gets to know a new team and vice versa but he's going to give it his best shot with a goal to bring home a World Championship.

"For me to go out on top would be a great cap for my career," Villooto said in an interview with Kawasaki Motors. I would get to say I won a world championship. If it doesn't happen I'm still going to be happy where I am at."

As a result of Villopoto's presence, the 2015 MXGP season is also getting stronger television coverage as CBS Sports Network plans to air the entire season on a same-day delay broadcast in the United States and Canada. The final round will be live.

Round 1 of the 2015 MXGP World Championship is Saturday at the Losail Motocross Track in Doha, Qatar.