(CNN) -- MotoGP world champion Valentino Rossi began his title defense with a fine victory in the season-opener in Qatar on Sunday.
Rossi won under the floodlights from Yamaha teammate Jorge Lorenzo with Italy's Andrea Dovizioso on a Honda in third place.
But Australia's Caser Stoner, who was bidding for his fourth straight win in Qatar, crashed out on the fifth lap having started from pole position.
Ducati's Stoner had dominated the practice sessions and qualifying, but was passed by Dani Pedrosa on his Honda on the first corner.
Former world champion Stoner regained the lead, but with 17 laps remaining he lost control of the front end of his machine and his race was over.
That left Rossi in first place and although he briefly lost the lead to Dovizioso, he was soon back in front and won by over a second from Lorenzo, who charged into the second podium place from fourth.
In the new Moto2 category, which has replaced the 250cc series, Japan's Shoya Tomizawa became the inaugural winner as he came from ninth on the grid to claim victory by four seconds.
Spanish rider Nicolas Terol won the 125cc race from compatriots Efren Vasquez and Marc Marquez.