Top ten is led by Bagnaia ahead of Vinales, Alex Marquez, Espargaro, Martin, Marc Marquez, Binder, Bastianini, Raul Fernandez and Morbidelli.
Espargaro is being stretchered away but he was moving prior to that.
Huge crash for Aleix Espargaro at the final chicane. It was a highside which has brought out yellow flags meaning no one will be able to go faster.
Bastianini has crashed
Huge front-end wobble for Marc Marquez who was on a lap good enough for the top three. Bagnaia meanwhile ahs gone back into top spot ahead of Vinales.
20 minutes remaining and the entire grid is in pit lane except for Bagnaia and Martin.
Marquez makes a big improvement of five tenths as he goes second quickest behind Bagnaia.
Marc Marquez has already decided to fit a soft front and rear tyre with 28 minutes still on the board.
Here we go... 30 minutes to go and Bagnaia is already into the 1m 31s barrier as he extends his lead by over three tenths.
Big moment for Enea Bastianini at turn 12 as he nearly highsided after losing the rear for a split second.
Bagnaia still has a lead of one tenth over title rival Martin, with Vinales and Acosta following closely.
Track limits are proving difficult to get on top of once again as Maverick Vinales sees his second fastest time deleted.
It's currently a Ducati 1-2-3 with Martin leading the way from Bagnaia and Marc Marquez.
Pit lane is open as the all-important second practice gets underway at Assen.
The final MotoGP practice of today has been delayed.
Good afternoon and welcome back to Friday practice at Assen. Second practice is coming up shortly with the top ten automatically advancing to Saturday's Q2.
Update: Di Giannantonio has had his best time deleted which means he drops to seventh place.
Di Giannantonio takes top spot ahead of Bagnaia, M. Marquez, R. Fernandez, Quartararo, Vinales, Espargaro, Alex Marquez, Binder and Martin.
Fabio Di Giannantonio goes quickest from Bagnaia, while Marc Marquez remains third despite improving his time.
We're not expecting many riders to go for a time attack with 'Practice' to come this afternoon. But there could still be changes to the order.
More fast laps are coming in as Bagnaia regains top spot ahead of Alex Marquez, who had gone top ahead of Fernandez prior to Bagnaia's 1:32.625s.
Big front-end moment for Marco Bezzecchi coming through turns 14 and 15.
Marquez is still top ahead of Martin, Vinales, Bastianini, Alex Marquez, Bezzecchi, Quartararo, Raul Fernandez, Bagnaia and Acosta.