Valentino Rossi has won his seventh MotoGP title, one round early, by finishing third in a wet and wild Malaysian Grand Prix dominated by Casey Stoner.

The race was delayed when - after two days of dry practice and qualifying, and dry conditions for the 125 and 250cc races - rain began pouring down on the Sepang circuit 25 minutes before the planned MotoGP start.

Further drama followed when second on the grid Jorge Lorenzo - the only rider still able to deprive Fiat Yamaha team-mate Rossi of the title - was forced to start from the back of the field 'having failed to join his starting position on time'. Lorenzo's number one bike had refused to start in the pits, prompting him to switch to his spare machine.

At the other end of the grid, Rossi began the race from his seventh pole of the year and needing only fourth place to secure the title before Valencia - even if Lorenzo won the race.

The 21-lap main event began on a fully wet track, with rain still falling, and saw Rossi attempt to keep his advantage by out-braking perennial fast-starter Dani Pedrosa into turn one - a move that backfired when the Italian ran wide and was swallowed by the pack.

A fired-up Lorenzo exited the first turns in eleventh and had overtaken Rossi on his way to eighth by the end of the opening lap! Rossi crossed the line tenth, while up front Stoner had overtaken Pedrosa to lead the field, with Pedrosa's Repsol Honda team-mate Andrea Dovizioso third.

Ducati star Stoner stormed to a six-second lead over Pedrosa within four laps, by which time Lorenzo and Rossi had settled into seventh and eighth.

Lorenzo then overtook Suzuki's Loris Capirossi, a move mirrored by Rossi, but Nicky Hayden offered tougher resistance to the young Spaniard - who took five attempts to pass the Ducati rider.

The #99 gained fourth place from countryman Toni Elias on lap seven, but Rossi continued to follow his team-mate's every move up the order - then, having gained confidence in the conditions, calmly outbraked Lorenzo on lap eight.

By the halfway point Stoner was 15 seconds ahead of Pedrosa, while Dovizioso was just one second behind the #3 with Rossi and Lorenzo five seconds from the final podium position.

Rossi gained breathing room over Lorenzo during the second half of the race - by which time the track was showing signs of drying - as his target switched back to his pre-race objective of celebrating his latest world title with a podium finish.

That was handed to him when Dovizioso span out of third place on lap 15, leaving Rossi with a 2.5sec gap to Pedrosa and second position.

But Pedrosa maintained his pace and Rossi rode to a safe third place - more than enough to claim the 2009 MotoGP World Championship. The Doctor now holds a 41 point lead over Lorenzo with just 25 points remaining at the final round.

Seven MotoGP titles is just one less than the all-time premier-class record of eight by Giacomo Agostini, while nine world championships in all classes puts Rossi equal third in history alongside Mike Hailwood and Carlo Ubbiali - behind only Angel Nieto (13) and Agostini (15).

The 30-year-old celebrated his latest title triumph with a huge wheelie over the finish line, before receiving a hearty handshake from Stoner and Lorenzo.

Rossi then met his waiting fan club for a pre-arranged celebration at the side of the track, which saw Rossi wear a special t-shirt and helmet with the number 9 on stating that 'old hens make the best broth! The Italian was then given a live hen wearing the same championship clothing!

Rossi has won six of the 16 races this season, with four wins for Lorenzo, four for Stoner and one each for Pedrosa and Dovizioso.

Stoner proved untouchable throughout the race and rode to victory by 14.666 seconds over Pedrosa - the Australian having now finished second, first and first since his comeback from a three-round hiatus to treat fatigue problems.

Stoner will start the final round 11 points ahead of Pedrosa and on target to claim third in the final championship standings, although Pedrosa was happy to take his first wet podium on Sunday.

Fourth place for Lorenzo was an impressive achievement from last on the grid and marked the first time this year that he has finished a race off the podium, while Hayden - taken out by Lorenzo one week earlier in Australia - gained vital points with fifth.

Chris Vermeulen used his wet weather skills to ride from 14th to sixth in his penultimate appearance for Rizla Suzuki, while Elias claimed seventh for Honda Gresini and Marco Melandri eighth for Hayate.

Capirossi dropped back to ninth on the second GSV-R with Mika Kallio rounding out the top ten for Pramac Ducati, just 1.2sec ahead of team-mate Aleix Espargaro. Supersub Espargaro was riding in only his third MotoGP race, in place of the injured Niccolo Canepa, ahead of a full season alongside Kallio in 2010.

Monster Yamaha Tech 3 riders Colin Edwards and James Toseland had a miserable day, finishing just 13th and 15th - either side of rookie Gabor Talmacsi (Scot Honda).

Despite the conditions, and total lack of wet track time prior to the race, LCR Honda's Randy de Puniet was the only rider other than Dovizioso to crash out.

Dovizioso is now just four points in front of Edwards for fifth in the championship, with Melandri and Capirossi tied for seventh.

The 17th and final round of the 2009 MotoGP World Championship will take place at Valencia from November 6-8.

Malaysian Grand Prix:

1. Stoner
2. Pedrosa
3. Rossi
4. Lorenzo
5. Hayden
6. Vermeulen
7. Elias
8. Melandri
9. Capirossi
10. de Angelis
11. Kallio
12. Espargaro
13. Edwards
14. Talmacsi
15. Toseland