Australian Anthony West has announced his switch to MotoGP after Yamaha allowed him to buy out his contract to race for them in the world Supersport series.
The 250cc Grand Prix race winner tested for Kawasaki in Barcelona last week and has been tipped to replace injured Frenchman Olivier Jacque for the remainder of the season.
Confirmation was expected at the British Grand Prix at Donington Park on Thursday, before the first practice session on Friday.
"I feel I've got my career back on track," West, 25, said in a Yamaha statement, without naming his new employers. "To leave Yamaha now is sad but it's such a great chance for me to follow my dream to go to MotoGP.
"The financial compensation I've got to pay is severe but I've got the chance to show what I can do on a MotoGP bike and I hope it's worth it."
West last competed in the top category in 2001, when he rode a privately-entered 500cc Honda.