Rossi hopes to try out new engine tomorrow

The Italian had been due to evaluate it in second free practice today, but with the session cancelled due to a downpour, those plans were abandoned.

Yamaha are hoping that the new engine, which was tried out in post-race testing at Brno, will deliver a bit more top speed to help Rossi take the fight to title rival Casey Stoner on the Ducati.

"I didn't use the new engine today because the programme was to use it this afternoon," said Rossi. "We started with the normal one, the Brno race spec one, and we will try the new one tomorrow morning.

"We will try the performance and if it is faster then it is ready (to race). In the test the difference was especially in fifth and sixth gear. The engine pushed a little bit more, and we have a bit more speed at the top."

Rossi is currently 60 points behind Stoner in the title standings and although he does not think this weekend's race at Misano is his last chance to turn things around, he admits it will be an important race for the title.

"The last chance, no?" he said. "The difference in the championship is quite big and the difference in performance is quite big. It is not the last chance, but it is an important race for sure."

When asked whether he expected this weekend to be harder than his win at Mugello earlier this year, he said: "I think for sure more difficult.

"The situation is a little bit changed and it is more difficult to try and win. But for sure it is so important because here in Misano it is close to the place where I grew up, so it is important for me. We try and we see."