Reigning seven time MotoGP world champion Valentino Rossi has revealed he is still one week short of being fully fit after his shoulder 'tried to come out' in a motocross training accident.

When first made public, Rossi's injury was described as simply 'bruising', but when asked to provide a description of the damage during the pre-event press conference for this weekend's Spanish Grand Prix it sounded more serious.

"The shoulder didn't come out, didn't dislocate, but it tried to come out," revealed the Fiat Yamaha rider. "So it was lucky it did not come out. The muscle resisted. But all the different muscles of the shoulder are stretched and also the ligament. And I also have a small, small crack in the bone."

The Italian, winner at the Qatar season opener, was then fortunate to benefit from an extra week off - after the cancellation of the planned Japanese round due to the flight ban caused by the Icelandic volcano - but will be riding wounded this weekend.

"Usually this type of injury needs three weeks. Today is two weeks so I need another seven days to be back at 100 percent," he said.

And despite winning at round one, after Casey Stoner had crashed from a confident lead, Rossi was visibly struggling for top speed in Qatar.

"We are a little bit worried, but we always suffered in Qatar a bit with top speed so we need to wait and see here, at a completely different track," he said.

"Also there was wind at Qatar and the gear ratio was not perfect. In fact I had the last top speed [in the race] so we hope to recover to more of less the centre of the group for top speed."

Rossi won by 2,7sec from Honda's Dani Pedrosa at Jerez last season, with Casey Stoner a distant third.

First free practice at Jerez takes place on Friday.