Northern Ireland rider Eugene Laverty says Yamaha's decision not to compete in next year's World Superbikes was a huge shock.
Laverty, who had two second places in Sunday's round at Silvertsone, lies fourth in the current series.
The decision leaves the Toomebridge man and stablemate Marco Melandri looking for a new team for 2012.
"It is really disappointing for the entire team, a great bunch of guys," Laverty said on his Twitter account.
In May, Laverty had his first World Superbike victories when he won both races at the Italian round in Monza.
In 2009 and 2010, 25-year-old Laverty was runner-up in the World Supersport Championship.