Yamaha has called up test rider Katsuyuki Nakasuga to replace Ben Spies for the MotoGP season finale at Valencia.
Spies' Yamaha career came to a premature end when it emerged that he required surgery to shoulder injuries sustained in his Sepang crash last weekend.
The American is moving to Ducati's revamped second team next season after a four-year association with Yamaha that began when he won the World Superbike title at the first attempt in 2009.
Double Japanese Superbike champion Nakasuga stood in for Jorge Lorenzo at Yamaha in the final rounds of the 2011 season after the Spaniard sustained a hand injury at Phillip Island.
Nakasuga went on to finish sixth at Valencia. The 31-year-old given another Yamaha factory ride as a wildcard in this year's Motegi race, where he took ninth.