Valentino Rossi says he will not be fully fit for the start of the 2011 season in March, the Italian admitting his recovery is going slower than he was hoping for.
Rossi had surgery in November last year following a long-lasting injury on his shoulder.
In his first appearance as an official Ducati rider, Rossi admitted he will need more time to be 100 per cent ready.
"I had hoped to feel a bit better, there's a lot of work to be done but it's a nice challenge to be in decent form for the February test," Rossi told a news conference at Ducati's annual ski retreat on Tuesday.
"At the first race of the year, in Malaysia on 20 March, I won't be in top form, but I hope I can feel well on the bike. It's a race against time, the situation with the shoulder was more serious than we had expected."
He added: "I aim to be at 100% in April/May. I hope the fans are patient. For sure I'm not a twenty-year-old anymore unfortunately, but the crashes in motocross and at Mugello could have happened anyway. I've never considered retiring,
"I'm eager, this change gives me many more motivations, so I hope to have a few years at the top."
Rossi, who missed several races last year after he broke his leg during the Italian GP, believes reigning champion and now Honda rider Casey Stoner will be his main rivals this season.
"The former knows the bike perfectly, but the latter has the Honda and that will be very important," he said.
"Stoner went fast with this bike, he has great talent in adapting to all conditions and had a great feeling with the bike, something I don't yet have at the moment. That's why I'll have to do a lot of running with it."
Speaking about the new Ducati bike, the Italian, who left Yamaha after seven years, added: "It's different from every other bike, it's a real prototype, a different concept from the Japanese manufacturers'. You must have a slightly rougher style to race with the Desmosedici."