Ben Spies has been diagnosed with a dislocated left ankle following his crash on the way to the grid at Estoril.
The Tech 3 Yamaha rider had a high-side at Turn 4 on his sighting lap, with all the riders trying to make the most of their reconnaissance outings as they had not had any other chance to ride on a dry track during the rain-blighted weekend.
Spies struggled to stand up after the crash and was taken to the medical center, which it was soon confirmed that he had dislocated his ankle.
The injury jeopardizes both Spies' participation in the season finale at Valencia next weekend, and his planned first test with the factory Yamaha team afterward. The American has been promoted to the works squad to replace Ducati-bound Valentino Rossi for 2011.