Valentino Rossi's Ducati MotoGP race debut ended with a less than spectacular seventh place in Sunday's Qatar Grand Prix.

The result reflected a difficult winter adapting to the Desmosedici and a lack of strength from his healing shoulder.

But the seven time MotoGP champion did show flashes of his usual form as he dived for second place into turn one - before spending much of the race battling with Yamaha replacement Ben Spies for sixth.

Rossi, who was the top Ducati rider, set the seventh fastest race lap, 0.687sec behind Honda race winner Casey Stoner's best.

"For sure we're not here to get seventh-place finishes, but there are also positive things from this race, starting with the times, because we were lapping pretty quickly," said Rossi. "I had a great start, and that was a nice feeling because the horsepower that this bike has really helps it to launch.

"Then I made a small error in the first turn, which is a shame because I got stuck behind Barbera for a few laps. Otherwise I would have been closer to Simoncelli and Dovizioso [4th and 5th], since anyway there was a period when I lapped with them.

"I wouldn't have beaten them though, because at the end of the race, I'm no longer able to ride like I have to.

"I'm not referring to the Ducati because even last year, after I hurt my shoulder, I had the same problems in the latter parts of the races, and since the two bikes are so different, it means that it's really a matter of me not being physically right.

"It's not just that. We also have to improve the bike because the others have clearly made a step forward since last year.

"Still, I learned a lot in this test and in this race, and we've already given very specific instructions about what must be done in the long term, in order to improve for the second half of the season for example.

"In the near term, on the other hand, we'll work on the setup, we'll keep gathering experience, and I'll continue exercising and doing everything I can to recuperate physically."

Rossi's best lap was half-a-second slower than Stoner had been on an GP10 in last year's race.

Team-mate Nicky Hayden was ninth after almost running over Randy de Puniet on the first lap.

"I got a bad start in the race, and then when de Puniet crashed, I just about ran over him and had to come to a complete stop. I'm happy I didn't run into him, but that was a bad break, because I was dead last with a gap to the next person," said Hayden.

"I started picking my way through, and once I got into ninth, I got into a decent rhythm and started doing my pace. I was trying to catch Edwards because I thought it would've been nice to have a last-lap race with him, but I didn't quite get to him.

"It's been a tough weekend for me on and off the track, but everybody around here is working to the maximum. They're the first ones in and the last ones out. I can't be happy with the ride, but I came from dead last, and my fastest lap was my last one.

"We've got a lot of work to do, but it's just one race, and no one can say we weren't trying."