Apr.11 (GMM) Reigning MotoGP champion Casey Stoner has played down suggestions that Michael Schumacher could already be quick enough to compete at the highest level of motorcycle racing.

The seven time world champion has been dabbling on two wheels since hanging up his formula one helmet, including recently stepping in at a Ducati test when the Italian team's regular test rider was injured.

It emerged from the Mugello test that 39-year-old Schumacher's best lap was about 8 seconds off the pace of race riders Stoner and Marco Melandri.

Stoner, an Australian, dismissed reports that the German can now - as is the case at Ferrari - be referred to as Ducati's official occasional test rider.

"Michael's not testing anything. He's just riding a bike, he's having fun," he told Speed TV.

"No matter how much experience he has in F1 he would need to learn to ride a bike a little faster before he started giving advice on electronic systems and suspension."

Stoner, 22, agrees however that Schumacher's riding is "quite exceptional" for someone with very little experience on two wheeled racers.

Schumacher's manager, Willi Weber, agrees that the German is simply making the most of his professional retirement.

"He only lasts two minutes on the sofa," he told Germany's Bild newspaper.

"It is impossible for him to do nothing," Weber added.