Dani Pedrosa closed in further on MotoGP title leader Jorge Lorenzo by claiming his sixth win of the year in a wet, wild and shortened Malaysian Grand Prix at Sepang.

The race began on a soaking track after an earlier thunderstorm and with intermittent rain still falling. That clearly meant full wet settings, but also a choice to be made between the hard and soft specification wet tyres.

Many of the leading riders had completed only a handful of wet laps during practice and some none at all.

The Yamaha riders all went for the soft rear - including Lorenzo and fellow front row starter Andrea Dovizioso - with second on the grid Pedrosa electing for the harder rear, as did the other RCV competitors and factory Ducati riders.

Lorenzo and Pedrosa soon broke away from the pursuing pack, pushing six seconds ahead of next best Casey Stoner by the halfway stage of the 20 laps.

Pedrosa made his winning pass into the final chicane at the end of lap 10 and eased away from the Yamaha rider, just as the rain began to intensify.

Lorenzo, who began signalling for the race to be stopped, was also being reeled in by Stoner - although the Yamaha star was still two seconds clear as he headed for the final turn on lap 14 of 20...

It was then that Lorenzo suffered a big front-end moment, the Spaniard just keeping control of his M1 but with Stoner right on his rear wheel as he exited the turn to be greeted by red flags at the finish line.

Lorenzo later explained that the tread on his soft rear tyre had been worn down in the 'not so wet' opening laps.

After the formality of waiting to see if conditions would improve enough for a restart, the results were declared from the end of lap 13, meaning a 3.7s victory - his first in the wet - for Pedrosa over Lorenzo, with Stoner +7.4s in third.

Pedrosa, who has won five of the last six races, is now 23 points from Lorenzo with two rounds to go.

Behind the podium finishers, Ducati riders Nicky Hayden and Valentino Rossi were credited with fourth and fifth.

Hayden improved steadily from eighth on the opening lap, while Rossi - who had shot from eleventh to fifth at the start - suddenly dropped to ninth on lap nine. The Italian, helped by the mistakes of others, then returned to fifth by the stoppage.

Gresini Honda's Alvaro Bautista lost a position to Rossi on the final lap, with Pramac Ducati's Hector Barbera staying out of trouble on his way to seventh.

Aleix Espargaro (Aspar) and James Ellison (PBM) led the CRT challenge in eighth and ninth with Cardion AB Ducati's Karel Abraham completing the top ten.

Lorenzo was the only Yamaha rider not to fall, with team-mate Ben Spies the highest profile victim of the conditions, suffering a shoulder injury after highsiding from his Yamaha.

Tech 3 M1 riders Cal Crutchlow and Andrea Dovizioso, LCR Honda's Stefan Bradl and CRT riders Randy de Puniet, Ivan Silva and Roberto Rolfo also crashed.

Spies fell with five laps to go, and the others all within three laps of the red flag, the period when the rain intensified.

Dovizioso, who had got a big slide at the start and almost collected Spies, was closing on Stoner for third place when he slid off. The Italian rejoined and was thus classified 13th and last.

MotoGP now heads straight for the Australian Grand Prix at Phillip Island, the third race in three weekends, where Stoner will be chasing a sixth win in a row on his final home appearance before retirement.

Malaysian Grand Prix:

1. Dani Pedrosa
2. Jorge Lorenzo
3. Casey Stoner
4. Nicky Hayden
5. Valentino Rossi
6. Alvaro Bautista
7. Hector Barbera
8. Aleix Espargaro
9. James Ellison
10. Karel Abraham
11. Danilo Petrucci
12. Michele Pirro
13. Andrea Dovizioso
Stefan Bradl
Cal Crutchlow
Randy De Puniet
Ivan Silva
Colin Edwards
Ben Spies
Roberto Rolfo