Lenovo Ducati's Pecco Bagnaia has overturned a 91-point deficit to reigning MotoGP champion Fabio Quartararo and extended it to 105 - probably the biggest comeback in motorsport history.

This weekend, Sepang hosts his first chance to take that first premier class crown, with four contenders remaining.

Bagnaia is champion if:

He wins and Quartararo doesn’t finish on the podium
If he finishes P2, Quartararo doesn’t finish better than P7 and Aleix Espargaro (Aprilia Racing) doesn’t win
If he finishes P3, Quartararo doesn’t finish better than P11 and Aleix Espargaro doesn’t finish on the podium
He finishes P4, Quartararo doesn’t finish better than P14 and Aleix Espargaro doesn’t finish on the podium
He finishes P5, Quartararo fails to score any points and Aleix Espargaro doesn’t finish on the podium

For Enea Bastianini, meanwhile, it's a final stand too. He's 42 points in arrears so the Italian is on the verge of falling out of contention if that gap is more than 24 points at the flag.