LOS ANGELES (Reuters) - Jorge Lorenzo needs to pass a medical test before taking part in Sunday's U.S. MotoGP following a crash just moments after snatching pole position.

The Spaniard was taken from the Laguna Seca circuit in an ambulance after he tumbled over the handlebars and slid into a sand trap at high speed at the end of Saturday's qualifying.

The official MotoGP website (www.motogp.com) said initial tests showed he had a partially dislocated right shoulder and a bruised right foot, but a decision on whether he could race would not be made until Sunday.

Lorenzo, currently second in the championship standings, had taken pole position with a fastest qualifying time of one minute 21.678 seconds.

His Yamaha team mate and championship leader Valentino Rossi was second quickest, 0.167 behind, with Australian Casey Stoner third despite crashing heavily on his Ducati.

Dani Pedrosa qualified fourth ahead of Andrea Dovizioso and Toni Elias.

(Reporting by Julian Linden in Sydney; Editing by Greg Stutchbury)