Reigning MotoGP champion Casey Stoner has given a damning assessment of Valentino Rossi's time at Ducati.

Stoner won Ducati's only MotoGP title at his first attempt in 2007 and had scored 23 race wins for the factory by the time he left for Honda at the start of last season.

Rossi, accompanied by his team of mechanics, took Stoner's place at Ducati with the aim of becoming the first rider to win premier-class titles with three different manufacturers.

However the seven time MotoGP title winner has managed just two podiums from 27 races and will now return to Yamaha next season.

Stoner - who has long felt that Rossi and crew chief Jerry Burgess didn't give him the credit he deserved at Ducati - cited comments of a quick fix to the handling problems on the Desmosedici as an example of how they have been made to 'eat their words'.

AAP quotes Stoner as saying: "Jerry [said] that it would take him 80 seconds to fix that bike and that it was a simple issue and now they have had almost two years and have not made any inroads.

"Valentino obviously doesn't want to push limits and ride a bike that is not perfect, he has admitted that."

Stoner added: "I just feel completely sorry for Ducati that Valentino has gone there and done nothing but complain about the bike for almost two years."

Stoner and Rossi have long endured a fractious relationship, although they only fought each other directly for the title during the 2007 and 2008 seasons.

Stoner - the most successful MotoGP rider since 2006 - will retire at the end of this season, while Ducati is yet to announce Rossi's replacement.