The main question on Valentino Rossi's mind ahead of his Yamaha MotoGP return was whether he could adapt to the 'new' kind of riding style perfected by Jorge Lorenzo, Dani Pedrosa and Casey Stoner.

Fresh from suffering the only winless seasons of his 17-year grand prix career at Ducati, a relieved Rossi set competitive times from the start of the Sepang test - his first dry laps on an M1 since he left Yamaha in 2010.

"I was quite sure that after two bad seasons I had not forgotten how to ride. But in the last two seasons the way to ride the bike has changed very much, especially the electronics and the tyres," Rossi explained.

"The riding style of the top guys - Stoner, Pedrosa and Lorenzo - is very different compared to 2008 and 2009 [when Rossi won his most recent titles]. So I have to change a lot and I didn't know if I am able to.

"Now, after the first test, I feel a lot more confident because with the M1 if I try to modify something, it works - with my riding style. Unfortunately, in the last two years, never."

Reflecting further on the Ducati disappointment, Rossi - a world champion on Aprilia, Honda and Yamaha machinery - avoided any finger pointing.

"I didn't continue with Ducati because I am sure it is not my bike. This is the main reason," he shrugged.

Rossi added: "I won almost every challenge in my career except Ducati. Anyway, if I had remained with Yamaha [in 2011] then I would feel more tired now.

"After the last two seasons, I feel younger and more motivated."

Rossi finished the opening Malaysian test in third place, 0.442s from Honda's Dani Pedrosa and 0.113s from team-mate and reigning double champion Jorge Lorenzo.

The chance to be competitive again has clearly been a breath of fresh air for the 34-year-old.

"It is another world! Like I do another sport!" Rossi said of being back in contention. "I know it will be very hard this year, but I can start the championship with the target to maybe fight with Lorenzo and Pedrosa.

"The motivation is 1000 times more than in the last years, where you know you can fight for sixth place."

But that doesn't mean he underestimates the challenge of taking on the likes Lorenzo, whose level Rossi feels has only improved since the last time they shared a (then divided) pit garage.

"I think now Lorenzo is perfect because he is very fast in every condition, rarely makes mistakes, has a high level of concentration and his race simulations are very strong," said Rossi.

"He is at the top. In 2010 he was already very strong and now he is even better."

Lorenzo won his first MotoGP title in 2010, although fans were denied a full contest between the Yamaha stars when Rossi broke his leg at Mugello. Lorenzo was leading the standings at the time of Rossi's fall.

The second Sepang test will take place from February 26-28.