"The balance I would say is positive; particularly with race tyres," he declared. "It was hard work doing a race simulation in this heat and at one point I slowed down a bit because the important thing was to finish our first race simulation with Bridgestone. It was generally positive; overall my pace was better than in the race last year and I did a 2min 1secs on my final lap, so the tyres are consistent and I like them."

One specific area of winter improvement, combining both bike and tyres, has been the M1's behaviour under heavy braking.

"It seems easier to slow the bike down on the Bridgestones," said Rossi. "Last year under braking we had a problem with the electronics and engine braking, which has also been improved. Now the bike seems to stop better. It seems to be better balanced, whereas last year on occasions if I went in too quickly the bike would do things I wasn't expecting."

Rossi's tyre change may be the most visible difference for 2008, but a more hidden development also came to light at Sepang.

After appearing to back away from a pneumatic-valve engine, following problems last year, Yamaha has restarted the project - and Rossi is already certain he'll be racing the engine, currently only available to the factory team, at Qatar on March 9.

"The pneumatic-valve engine is going pretty well, particularly as we've covered so many kilometres without having to change it. It also seems a bit faster than last year and we've had no problems, so we know we can use this engine this year," said Rossi confidently. "We also tried a slightly different chassis which seems to be quick and a bit more agile, so that's positive too."

Fiat Yamaha will miss next week's Phillip Island test, but return to Sepang from February 5-7.