Speculation is rising that Yamaha bosses are poised to quit the World Superbike Championship if Ben Spies defects to the Monster Yamaha MotoGP team, leaving their official effort to the fledgling Stiggy Motor Sport team to take on.

Johan Stigefelt is known to be keen to switch to Yamaha after a lack of support from Honda this year and is in line to run a satellite team if the official squad remains in the series.

But if current works rider Spies decides to go to MotoGP and the Monster Yamaha team, that will give Yamaha the excuse they need to stop spending money in World Superbikes and hand the number one spot to Stiggy.

The Swedish ex-racer has been pushing current rider Leon Haslam to sign for next season  but the former HM Plant Honda man has plenty of options open to him, including Alstare Suzuki and Kawasaki.