Just when Ben Spies looked to have finally put his right shoulder injuries behind him, the Texan suffered a dislocation to his left shoulder during Saturday practice for his MotoGP comeback at Indianapolis.

The Pramac Ducati rider, whose previous shoulder injuries date back to last October's Malaysian race, had been aiming to take part in his first grand prix since round two in Texas.

Instead he will miss not only Sunday's Indianapolis race but is in major doubt for next weekend's Brno round - with Silverstone just one week after that - and must have further scans to determine if he also has a wrist fracture.

"I was back and starting to feel good, now we have another shoulder injury, but this time on the left," said Spies. "Right now I still need to go back to Dallas have some CT scans on my wrist to see if there's anything broken there, but definitely on my shoulder we have a grade 3 separation."

The highside fall appears to have been caused by the absence of traction control in first gear on the Ducati, a trait Spies had forgotten.

"Regarding the crash, I was going out on the first lap when I made a mistake and spun the rear tyre and highsided. I'm just sorry for the team and frustrated for the fans because I was looking forward to being out there. We were starting to feel good but now we're back at square one."

Worryingly for Spies, team-mate Andea Iannone dislocated his shoulder during the German round in mid-July - and is still struggling with the pain.