Bagnaia now 1.3s clear of Martin. The race leader is lapping in the 1m44s and was the only one in that bracket last time around.
Meanwhile, Bastianini is coming for Marquez. He is 1.2s behind after the Gresini rider ran wide at Turn 1.
It's hard to know at this stage how much tyre preservation is playing a part in both Bagnaia and Martin's races.
The Pramac rider could well be giving his rear tyre a rest and making sure his front tyre doesn't get too hot for a late assault.
Big lap 12 for Bagnaia as his lead is back up to 1.1s over Martin.
Vinales has crashed at Turn 5. He was running 11th.
Bagnaia's lead is fairly stable at 0.9s from Martin. Marquez still third, with Bastianini 2.5s behind in fourth.
Binder is top KTM in fifth ahead of Morbidelli, Bezzecchi, Miller, Di Giannantonio and Espargaro.
Vinales is 11th from Quartararo, Zarco, R.Fernandez and Nakagami.
With the weather proving threatening, these next 14 laps are going to be the measure of the top two in the championship.
If there is rain, it's not affecting the leaders. Bagnaia is 0.7s clear of Martin at the start of lap 11. Marquez is 2.6s behind in third.
Bastianini is finally through on Binder for fourth.
Bagnaia's lead down to 0.6s, while race direction is waving the white flag which means it must be raining somewhere!
Bastianini tries on Binder at Turn 9 but runs wide and lets the KTM back through.
It's looking a bit darker around the Motegi circuit. Still 16 laps to go here.
Bagnaia's lead is 0.9s at the start of lap nine over Martin. Bastianini still hasn't been able to find a way through on Binder.
Acosta has been lapped by the leaders now.
Bagnaia's lead down to 0.8s at the start of lap eight.
Marquez is third and pulling away from Binder again, who in turn has Bastianini swarming all over him. The Ducati rider needs to get going soo if he wants to get into the podium battle and even have a sniff at the win.
Such is the massive difference between the GP24 and GP23 at this stage of the season now that Marquez is two seconds behind the top two.
Augusto Fernandez has crashed.
Are we finally about to see a proper head-to-head duel between the top two in the championship? I certainly hope so!
Onto lap seven and Bagnaia's lead is now down to 0.9s over Martin.
A 1m44.461s for Martin sees him close the gap to Bagnaia to 1.2s.
Marquez is 1.4s behind Martin.
Through all of the recent drama, Bastianini managed to find a way through on Miller to get to fifth.
Another terrible start to the race for Aprilia's Maverick Vinales, who has gone from the front row to 10th.
Marquez comes from a long way back to get third from Binder at Turn 5. He is now up to third.
Bagnaia sets a new fastest lap of 1m44.519s as his lead over Martin is now 1.5s over Martin.
Acosta has remounted and is last.
Bagnaia's lead is now 1.3s as a result of that crash, while Martin is now second after getting ahead of Binder at the end of lap three.
Acosta has crashed again! He is down at Turn 14 from second.
Bastianini is trying to get ahead of Miller now but he is being held at bay. He needs to move quickly to stop the leaders running away.
