(CNN) -- Jorge Lorenzo claimed pole position for the U.S.MotoGP at Laguna Seca but may not be fit to race after being stretchered away following Saturday's qualifying session.
Lorenzo is on pole for the U.S. MotoGP despite double about his participation for Sunday's race at Laguna Seca.
The Fiat Yamaha rider set a mark of one minute 21.678 seconds but both he and world championship rival Casey Stoner suffered crashes near the end of the session with the Spaniard taken away on a stretcher.
Stoner, of Ducati Marlboro, was third in 1:21.910, behind Fiat Yamaha's multiple world champion Valentino Rossi (1:21.845) and appeared to be walking unaided, albeit with a limp, after crashing on turn three.
His crash came just moments after Lorenzo, who had already been involved in a lowside crash earlier in the session, flipped his handlebars, landing on his shoulder and sliding 30 meters into the sand.
It is unclear whether either would be able to race on Sunday.
Dani Pedrosa was fourth with fellow-Honda riders Andrea Dovizioso and Toni Elias making up the second row.
Rossi leads the championship after securing his 100th win last weekend, with Lorenzo second and Stoner third.