Rossi feels Yamaha have work to do

The Italian passed Stoner for the lead last time out at Assen as he charged from 11th on the grid to take the win, but he believes that Stoner and Ducati will continue to be strong at every track.

"We know that Casey will be strong again, like he is everywhere this year," said Rossi. "We've got work to do still."

The 28-year-old admitted that while he feels that Yamaha are improving as the season goes on, they can not afford to have any bad weekends from now on if they want to close the gap in the standings.

"With Casey performing at such a high level at every race, 21 points is not a small amount so we have to be at the maximum," he added.

"We're not perfect yet, especially in the wet, but we're going in the right way and we'll keep pushing. We still have half the season left."

The next round of the season takes place at the Sachsenring, where Rossi won from 11th on the grid last year.

"I'm really looking forward to Sachsenring," he said. "Last year in Germany we qualified 11th and won, and last week in Assen we did the same thing.

"Of course, I would much rather start from the front but anyway I'm feeling confident. The bike works very well there and I've had a lot of good wins there in my career."