Home star Nicky Hayden has been declared unfit to race in Sunday's Indianapolis MotoGP.

The Ducati rider highsided heading into turn 14 with eight minutes of Saturday's qualifying hour remaining and was briefly knocked unconscious, prompting the deployment of red flags for the second time, after Casey Stoner's earlier fall.

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"After an initial check at the track's Medical Center, the American was transferred to Indianapolis' Methodist Hospital, where additional examinations revealed two small, non-displaced fractures to the second and third metacarpal on his right hand," said a Ducati statement.

"The results of the CAT were negative, and the American should be discharged this evening or tomorrow morning, but in any case he won't take part in the Grand Prix."

Hayden, who took his first Ducati podium at Indy in 2009, had qualified as the top Desmosedici rider in eighth place.

Reigning world champion Stoner suffered ankle ligament damage in his highside and is yet to be confirmed for the grand prix.

Ben Spies - who also suffered a heavy fall at the same turn - injured his shoulder but hopes to ride.