Australia's Casey Stoner was stretchered off the track after a crash on his Honda during qualifying on Saturday for the Indianapolis Grand Prix.
Stoner, the reigning MotoGP world champion and last year's winner at Indianapolis Motor Speedway, complained of pain in his left ankle at the circuit's medical center.
Stoner ranks third in this year's season points chase behind Jorge Lorenzo and second-place Dani Pedrosa, both of Spain.
Meanwhile, Speedway officials confirmed that Hector Faubel escaped serious injury in an earlier crash in the Moto3 division.
Faubel, who complained of chest and back pain, was taken to a local hospital for further examination.