Former MotoGP world champion Nicky Hayden waves goodbye to Honda on Sunday at the scene of their greatest triumph together two years ago.

The Ricardo Tormo circuit on the Western outskirts of Valencia provided the venue for one of the most dramatic season finishes in the 59 year history of grand prix racing when American Hayden clinched the 2006 MotoGP title for the Repsol Honda team from their former rider Valentino Rossi.

Hayden returns to compete in the final round of the 2008 Championship making his last appearance for the Honda team. Less than 24 hours later he will return to the circuit for his debut with Ducati Marlboro in preparation for the 2009 season, when he joins another former world champion Casey Stoner in the Italian team.

Current world champion Rossi has never forgotten that fateful day two years ago when, having already been passed by Hayden, he crashed out of the race to forfeit his title chance. Further misery was to follow last year when, riding through the pain of Saturday injuries, Rossi's Yamaha suffered a technical problem in the race - robbing him of the single point he needed to take second in the world championship from Honda's Dani Pedrosa.

This season, the Italian returns brimming with confidence - having already secured his sixth MotoGP crown, whilst also leading Yamaha to teams' and constructors' championship glory. After his ninth grand prix victory of the season in Malaysia last weekend, Rossi is in supreme form and relishing the opportunity to secure ten wins in one season on Sunday.

Spaniard Pedrosa won the race last year and he returns home fresh from an impressive second place behind Rossi in the searing heat of Malaysia. Both Pedrosa and his team have adjusted well following their switch to Bridgestone tyres and secured their third place in the championship with the Malaysia result. Pedrosa has won both previous Spanish rounds this season, with Michelin tyres.

Casey Stoner, whose painful sixth place finish in Malaysia was enough to secure the runner-up spot in the 2008 championship, could be forgiven for having his mind on other things at Valencia. On Monday and Tuesday after the race he will test the prototype 2009 Desmosedici Ducati. Two days later he enters an Italian hospital for an operation to mend his damaged left wrist which he broke five years ago. The 2007 world champion will be out of action for two and a half months following a bone graft operation.

Jorge Lorenzo in unable to challenge Pedrosa for third in the points, but the Estoril winner can make a small piece of MotoGP history by confirming fourth on Sunday. The Fiat Yamaha rider is currently 21 points ahead of fellow rookie Andrea Dovizioso and, by wrapping up the rookie of the year crown, will become the highest placed debutant since the four-stroke MotoGP class began in 2002.

Italian Dovizioso has also had a brilliant MotoGP debut season with the JIR Scot Honda team and secured his first MotoGP podium finish in Malaysia with a hard fought third place. He makes his last appearance for the team on Sunday before replacing Hayden at Repsol Honda next season.

By contrast, Valencia winner Marco Melandri has had a miserable time at Ducati and cuts short his two year contract to join Kawasaki next season. He replaces Australian Ant West who will compete in the World Supersport Championship next season. Popular Frenchman Sylvain Guintoli leaves the Alice Ducati team and will ride in the British Superbike Championship next year while his team-mate Tony Elias returns to the Gresini Honda team to partner Alex De Angelis. Finland's 250cc star Mika Kallio will replace him.

Japanese veteran Shinya Nakano has been in impressive form in the last three races but looks to be without a ride next season He has been replaced by Elias at Gresini Honda and the chances of him riding a third Kawasaki next season are remote. Nakano looks likely to become the official Honda test rider next season.

The biggest MotoGP farewell will be reserved for the Michelin tyre company. After so much success in the old 500cc two-stroke, 990 four-stroke and 800cc four-stroke classes they are leaving the Championship. Next year Bridgestone will be the sole supplier to all teams.

21-year-old Italian Marco Simoncelli clinched the 250cc World Championship with a third place in Malaysia. The Metis Gilera rider will want to end his superb season with a sixth win although Spaniard Alvaro Bautista is the man in form. The Aspar Aprilia rider has finished on the podium in the last nine grands prix and won his fourth grand prix of the season in Malaysia to clinch second place in the Championship. There is still a battle for third place with the departing Kallio, together with his KTM team, holding a 15 point advantage over local man Alex Debon.

Frenchman Mike Di Meglio is safe and sound as the 125cc World Champion but there is a tremendous battle for second place between the 2007 World Champion and Malaysian winner Gabor Talmacsi, Italian Simone Corsi and German teenager Stefan Bradl. They are separated by 19 points going into the final showdown.