New Yamaha MotoGP Test rider Jonas Folger is recovering from surgery after a collarbone injury while training on his motocross bike.

The German - a podium finisher for Tech3 Yamaha during his rookie 2017 MotoGP campaign only to be sidelined by fatigue issues - made his premier-class return with Yamaha at last month's Valencia test, setting the 20th fastest lap time (+1.5s).

Folger, who hopes to make at least one wild-card race appearance next season, now has until the end of January to recover before being needed by Yamaha at the Sepang test.