LOSAIL, Qatar (AFP) - Defending world champion Casey Stoner of Australia, on a Ducati, won the season-opening Qatar Grand Prix here on Sunday, the first world championship race to be held at night.

Rookie Jorge Lorenzo, who moved into the top flight MotoGP series after winning the last two 250cc titles, was second on his Yamaha, 5.323secs behind, with Honda's Dani Pedrosa taking third, more than 10secs off the pace.

"It's been a hard weekend for us," admitted Stoner who won here also last year but started Sunday's race from fourth on the grid.

"We didn't start well at all. I didn't have a lot of grip at the rear and people were knocking each other out of the road.

"But I managed to get in front where I felt comfortable and then do some reasonable lap times," added Stoner after his 11th MotoGP race win.

In a sensational start, Pedrosa stunned the field by taking a first lap lead from his eighth-place starting place as pole-sitter Lorenzo slipped back to fifth place.

But Valentino Rossi, a five-time world champion in the MotoGP series, then stormed into the lead on his Yamaha on the third lap with Pedrosa in second, Lorenzo in third and with Stoner biding his time on his Ducati in fourth spot.

The Australian then made his move on the eighth lap by taking the lead with Rossi relegated to third as 20-year-old Lorenzo took second spot.

Stoner, showing no ill-effects of a recent shoulder injury, gradually extended his lead and with seven of the 22 laps left, his advantage was more than a second over Lorenzo.

With five laps left, Pedrosa had pushed Rossi, whose Yamaha was on Bridgestone tyres, back to fourth while Stoner was hammering home his advantage at the front where his lead was over four seconds with two laps left.

Rossi's misery was compounded when another rookie, compatriot Andrea Dovizioso, went past him in his Honda on the final lap to grab fourth with Rossi having to settle for fifth place.

Sunday's race, held in chilly temperatures, was illuminated by 3,600 light fixtures generating 5.4 million watts of power - enough light to cover an area equivalent to 70 football pitches.

The bulbs are fixed on 1000 poles all linked together by almost 500 kilometres of wire and supported by 300,000 kilos of concrete.

Meanwhile, Italy's Mattia Pasini, on an Aprilia, won the 250cc race with Spain's Hector Barbera and Mika Kallio of Finland second and third respectively.

In the 125cc event, Spain's Sergio Gadea, on an Aprilia, took the chequered flag ahead of compatriot Joan Olive and Germany's Stefan Bradl.