Marlboro Ducati's Valentino Rossi faces a wait of up to three MotoGP races before he will see new parts that he hopes will fix the rear grip and stability problems he is experiencing on the current Desmosedici GP11.

The Doctor, who successfully debuted a new engine in today's Barcelona race, says that although he has now got a good feeling with the front, there is still a lot of work to do with the rear and going with an unknown setting in today's race, where he finished fifth, was a mistake.

"We fix well the front of the bike but we lose in other places especially the rear. For this reason Ducati is working on rear suspension, some linkages and we have to wait for those for two or three races," said the nine-times world champion.

"The good thing from today is the distance to Stoner and the victory is half what it was at Le Mans. I can see stoner for all of the race so that is good. We are not happy about fifth as yesterday we modified the rear to improve the stability of the bike which we were to try in warmup but unfortunately it was wet.

"It worked very well there as I was very fast so we decided to use it withough trying in the dry but I lose too much in corner entry as I don't have enough grip in rights. It also gave me some problems under braking so I was behind Dovi but could not push anymore. We made a mistake. We don't know this bike enough still."