In a frantic race from start to finish, the young Red Bull KTM rider held his nerve right until the end to take the chequered flag by just 0.038 seconds from Fabio Di Giannantonio on his Honda.
The win was sweetened for Binder, with both title rivals Jorge Navarro and Romano Fenati crashing out to give the South African a full 25 points extra in the title race.
He now leads Navarro by an impressive 49 points, with Fenati a full 60 behind the championship leader, and with 12 races left in the calendar those points could be invaluable come the Grand Prix of Valencia in November.