Marco Melandri's debut for Yamaha in the World Superbike Championship could be at risk after admitting he is concerned over whether he will be ready for the opening round in Australia.

The Italian, who makes the switch to World Superbikes after several successful seasons at MotoGP level, took to Twitter recently to reveal he has been feeling pain in his shoulder, though a subsequent update insisted it was him 'just getting old'.

However, Melandri has taken to the social networking site once more to suggest not all is well with the shoulder, adding that he is hoping he will be fit in time for the opening round in February.

"Bad present for Christmas... For sure better now than in a month... Hope to be ready for round 1..."

Though the opening round of the 2011 season is still two months away on February 27th, Melandri will go up against his rivals sooner than that in January when official pre-season testing gets underway. He will be partnered by Eugene Laverty.