Katsuyuki Nakasuga has been named as Yamaha's replacement for the injured Jorge Lorenzo ahead of this weekend's Malaysian Grand Prix at Sepang.
The 30-year-old has been involved with Yamaha's test programme for the YZR-M1 and for Bridgestone tyres, though this call up will represent his first-ever MotoGP start.
Currently classified third overall for Yamaha in the Superbike class of the All Japan Road Racing Championship, Nakasuga's experience of the grand prix class is limited having taken in just three 250GP starts at his home Japanese event in 2002, 2003 and 2004.
He takes the place of 2010 champion Lorenzo, who suffered an injury to his left ring finger in an accident at Phillip Island.
Lorenzo's participation in the season concluding Valencia Grand Prix is still to be decided, while Yamaha are yet to officially confirm that Ben Spies, who also missed the Australian race after crashing during practice, will be fit to ride at Sepang.