The 2009 MotoGP World Championship begins under floodlights in Qatar this weekend. Here is a team-by-team preview, followed by a summary of the main rule changes, heading into the new 17-round season...

Fiat Yamaha Team - Valentino Rossi (46), Jorge Lorenzo (99):

After his return to the top in 2008, Valentino Rossi arrives at the 2009 season-opener as an eight-time world champion and with a 'stable' technical package. The Italian and his Yamaha now have the benefit of a year's worth of Bridgestone tyre experience and The Doctor has been consistently fast in winter testing.

However, he was only third at the Qatar test and the desert circuit has not been Rossi's strongest venue in the past. Nevertheless, make no mistake, Rossi is once again the overwhelming title favourite heading into the new season.

Unlike Rossi, 2008 rookie of the year Jorge Lorenzo is new to Bridgestone tyres, but his gained momentum during a sometimes challenging winter 'apprenticeship' on the Japanese rubber, and took fourth position in the final Jerez test.

Lorenzo claims it will be difficult to repeat his stunning debut pole of one year ago, now that qualifying tyres have gone, but has his sights set on a firm podium challenge this weekend. Lorenzo finished second only to Casey Stoner at Qatar last year.

Ducati Marlboro Team - Casey Stoner (27), Nicky Hayden (69):

Casey Stoner may have lost his crown to Rossi last season, but the young Australian remains the most successful rider of the 800cc MotoGP era, with 16 wins to Rossi's 13, plus 25 podiums and 14 pole positions (since the start of 2007).

Stoner has also been fastest in every pre-season test he has attended, having missed November's Jerez outing due to wrist surgery, and was almost one second clear of nearest rival Lorenzo at the Qatar test.

But, as was proven last season, lap times and pole positions alone are not enough to beat Rossi and Stoner is approaching the new season with caution - and a pledge to be more aggressive in the races. Stoner has won at Qatar for the past two seasons and is considered the pre-event favourite this weekend.

Fellow former world champion Nicky Hayden has changed teams, motorcycles and tyres for 2009 and has been hit hard by the reduction in winter testing. The former Repsol Honda rider is yet to get fully comfortable on his new GP9, with its carbon fibre chassis and swingarm, but appears to have settled in well to his new surroundings and has formed a useful working relationship with Stoner.

A top six would probably be considered a success for Hayden this weekend.

Repsol Honda Team - Dani Pedrosa (3), Andrea Dovizioso (4):

The once-feared factory Honda team heads into the new season on its back foot, after an injury for Dani Pedrosa - Honda's only race winner since the end of 2006 - and a low-key winter for new signing Andrea Dovizioso.

Pedrosa might not even be able to ride this weekend, as he continues to recover from skin graft surgery to his knee - damaged at the Qatar test in early March - while Dovizioso is adamant more changes need to be made to the RC212V.

Dovi was the top Honda rider at the final Jerez test, but seventh position isn't what he expected as a factory RCV rider. Pedrosa meanwhile has been cautious about changing the RCV too much, as his intention had been to start the year with a well understood package.

Expect Repsol Honda to view the first few rounds of the season as a damage limitation exercise.

Monster Yamaha Tech 3 - Colin Edwards (5), James Toseland (52):

The top satellite team of last season returns with an unchanged line-up, but with new Monster Energy title sponsorship and a wall dividing its riders after a winter feud triggered by a swap of crew chiefs.

Colin Edwards has adapted to Bridgestone tyres like a duck to water, while James Toseland had suffered two huge accidents from the three 2009 pre-season tests as he continues to understand the characteristics of the Japanese rubber.

Edwards now needs to prove he can race as good as he tests, while Toseland needs to stay on two-wheels and regain vital confidence. Toseland qualified second to Lorenzo on his MotoGP debut at Qatar last season.

Rizla Suzuki MotoGP - Chris Vermeulen (7), Loris Capirossi (65):

The most improved manufacturer over the winter is undoubtedly Suzuki, whose revamped GSV-R set the third, fourth and third best lap time during the three pre-season tests - at Sepang, Qatar and Jerez respectively.

Veteran Loris Capirossi led the Suzuki challenge on two occasions, while Chris Vermeulen was the top man at Qatar. After such encouraging form, Paul Denning's team will surely be aiming for nothing less than a double top six finish this weekend - and hopefully a podium.

San Carlo Honda Gresini - Toni Elias (24), Alex de Angelis (15):

The return of Toni Elias and the arrival of a satellite RC212V for the Spaniard have been the main talking point at Honda Gresini this winter. Unfortunately, a factory Honda is no longer a guarantee of competiveness and Elias heads into the new season seeking a cure for rear traction problems, while satellite rider de Angelis will be most concerned with eliminating errors during his free season.

Team Scot - Yuki Takahashi (72):

The honour of being Honda's home grown MotoGP rider has fallen to rookie Yuki Takahashi for the 2009 season, who starts his first premier-class season within the familiar surrounding of Team Scot - for whom he rode in 250 - and with the knowledge of what the squad achieved last season with Andrea Dovizioso.

Pramac Racing - Mika Kallio (36), Niccolo Canepa (88):

All change for the satellite Ducati team with a double rookie line-up for 2009, but former 125 and 250GP title contender Mika Kallio has already proved competitive - highlighted by sixth place at the final Jerez test - while former Ducati test rider Niccolo Canepa has had more mixed fortunes in testing.

Hayate Racing Team - Marco Melandri (33):

Born out of the ashes of the Kawasaki Racing Team, Hayate will field Marco Melandri on 2009 ZX-RRs during what looks like being the team's first and last season of MotoGP competition.

The level of factory support is unknown, but Melandri has made clear progress during the two tests the team attended and might be able to claim a top ten this weekend.

After a nightmare season alongside Stoner at Ducati in 2008, Melandri may yet revel in his new underdog role as he seeks to secure a return to competitive machinery for 2010.

LCR Honda MotoGP - Randy de Puniet (14):

Randy de Puniet remains with LCR for a second season, with his and the team's number one priority being to convert the Frenchman's practice and qualifying speed into race results. A new approach has been devised and de Puniet appears to be gaining confidence with the pneumatic-valve satellite RCV.

Grupo Francisco Hernando - Sete Gibernau (59):

Making a popular return to MotoGP in 2009 is double world championship runner-up Sete Gibernau, riding a fifth Ducati for the newly-promoted Grupo Francisco Hernandez outfit, which fielded Pablo Nieto in 125 last season.

Nieto is now a joint team manager, alongside brother Gelete, and the young team's first priority is to find its feet in MotoGP, whilst providing nine-time race winner Gibernau with the technical package he needs.

Gibernau has repeatedly downplayed expectations, but most expect the 36-year-old Spaniard to run towards the front at some point this season - probably in the wet.

Main 2009 MotoGP rule changes:

* All riders on Bridgestone tyres, slick options limited to one soft and one hard compound at each race. No qualifying tyres.
* No Friday morning free practice session.
* Only five engines can be used for final seven rounds, 10 point penalty for additional engines.
* Only two post-race test sessions.