Title holder Valentino Rossi knows he will have to repeat his recent form if he is to keep his rivals at bay.

The Fiat Yamaha rider leads the world championship standings from team-mate Jorge Lorenzo and Ducati Marlboro's Casey Stoner.

But Rossi knows he will have his work cut out at the Sachsenring after finishing second to Repsol Honda's Dani Pedrosa during the last round at Laguna Seca in America.

That second place increased Rossi's lead over Lorenzo to nine points.

But even with Stoner suffering from anaemia the Australian is only a further seven points behind Lorenzo so Rossi knows there is no room for complacency with the series only half over.

Rossi said: "Thank goodness we've had some time to rest after the last two races because I was really quite tired after Laguna.

"The next two races are back to back and again it will be very hard, and it's also a very important stage of the championship, the halfway point."

Although Rossi admitted the track in Germany was not a personal favourite he revealed he was looking to build on his points lead.

"Sachsenring isn't one of my favourite tracks but I've had some great races there and generally it suits Yamaha well, which is good," he said.

"We need another good result to keep our lead because our rivals are so strong and we can't afford to make any mistakes.

"Last year there was a lot of rain in Germany but in fact we were able to take a great second place. I hope this year we can go one better."