Reigning MotoGP champion and 2009 title leader Valentino Rossi has expressed sadness at the withdraw of Casey Stoner from the next three rounds of the championship.

After winning two of the first five races, Stoner has battled a mystery energy-sapping illness for the last five rounds - and dropped from first to third in the title chase, 37 points behind Rossi and 12 points behind the second Fiat Yamaha of Jorge Lorenzo.

"I think first of all it is very bad for the championship," said Rossi. "To lose Casey is to lose one of the greatest riders and one of the guys fighting for the championship. It is a great pity. I would like a lot to have Casey on the track and fight with him. I hope he will come back soon."

Stoner won Ducati's first and so far only MotoGP World Championship in 2007.