But the real shock was second place for the Hayate Racing machine of Marco Melandri, who put his Ducati and Kawasaki nightmares firmly behind him.
Jorge Lorenzo has overtaken his Fiat Yamaha team-mate, the current world champion Valentino Rossi, in the MotoGP world championship after wining the French grand prix at Le Mans.
The Spanish rider finished 17.71sec ahead of Marco Melandri of Italy, with Dani Pedrosa of Spain beating Italy's Andrea Dovizioso into third place with a late burst of speed. Lorenzo leads the overall standings by a point after four races, with Rossi and Casey Stoner tied for second on 65 points.
Rossi had gone in early to switch to his second bike with slick tyres but that strategy proved to be his undoing as he slid off and then visited the pits several times – including once for a ride-through penalty for speeding in the pit lane – to get his tyre selection right.
Behind Lorenzo and Melandri were the Honda duo Dani Pedrosa and Andrea Dovizioso, with the Ducati of Stoner in fifth.
Chris Vermeulen (Suzuki) was sixth, Colin Edwards (Yamaha) finished seventh and Vermeulen's team-mate Loris Capirossi was eighth. James Toseland was ninth and Toni Elias (San Carlo Honda) 10th. Rossi came 16th and failed to score a championship point.
Melandri struggled to be competitive on the Ducati and also thought he might not be racing this season when Kawasaki pulled out of MotoGP.
A compromise deal struck by Kawasaki and series rights holders Dorna resulted in the Italian racing on machines supplied by the Japanese manufacturer and run under the Hayate Racing banner.
Melandri repaid the team with a fine second place behind Lorenzo, who had stayed out on the drying track with a bike running wet-weather tyres longer than most of his rivals.
Rossi could only finish 16th and failed to score a championship point, leaving the defending champion one point behind new leader Lorenzo in the standings and tied in second with Stoner on 65 points.
