Fiat Yamaha's Valentino Rossi has said serious grip problems were responsible for his lack of pace at the Estoril MotoGP round this afternoonm, limiting him to fourth place.

The Doctor, who was never in the race after lap four, had to watch as team-mate Jorge Lorenzo cleared off to finish the race seven seconds ahead of the returning Casey Stoner.

"It was a very difficult race for me. I was never able to be fast because I did not have enough grip in the rear and our tyre did not work well, but I think it was more a problem of setting," said Rossi.

"After a few laps I was in great difficulties and I immediately understood that this was not going to be "our" race. Throughout the practice sessions I had some problems but I thought that today I would be able to at least stay with Stoner and Pedrosa, but they made another step forward for the race and then there was no chance for me.

"On Friday I was three tenths off the pace and unfortunately this stayed the same all weekend and in the race today. Here in Estoril we struggled last year as well, so it might be that, with our setting, the rear tyre gets very hot and this causes a lack of grip.

"It is a pity that I am off the podium, but we have three more races and they are three great tracks. We must think race by race and we must work to understand what the problem was today in order to make sure that we fix it in time for Phillip Island."