The slippery track surface is illustrated by Jorge Martin fluffing both of his practice starts on the grid after the session ends.
afternoon action
Good morning/afternoon (depending on where you are joining us from today!) and welcome back to live coverage of the Indonesian GP.
Practice is due to begin in 20 minutes.
Update: Miguel Oliveira was diagnosed with a fracture of the right wrist after his FP1 highside.
The chequered flag waves for FP1.
Franco Morbidelli stays fastest with Aprilia's Maverick Vinales moving into second place, 0.221s behind the Pramac rider.
Jorge Martin likewise snatches a late third place.
All riders are still on medium rear tyres, saving their softs for when it matters, starting this afternoon with the top ten places for Qualifying 2.
Morbidelli is the first rider into the 1m 30s this weekend, putting him over half-a-second clear with 5mins remaining.
7mins left and Morbidelli is back on top, with Zarco in a Pramac sandwich ahead of Martin.
The only riders currently behind the absent Oliveira on the timesheets are Rins and Brad Binder.
Not for the first time, one of Quartararo's swingarm wings has worked loose. The Frenchman is currently 10th.
Meanwhile, Miguel Oliveira is on his way to the medical centre for checks.
Approaching the final ten minutes of the session and the top 8 is: Zarco, Martin, di Giannantonio, Bezzecchi, Nakagami, Bagnaia, Marc Marquez and Vinales.
Johann Zarco responds to team-mate Nakagami's speed by putting his LCR on top while chasing Martin.
Big highside for Miguel Oliveira at Turn 4. The Trackhouse rider is flung down the track and receives assistance from the marshals.
Takaaki Nakagami, the only RC213V rider still on the old Honda fairing, briefly goes fastest with a 1m 31.767s.
It doesn't last long with Martin edging 0.042s under the Japanese and Marco Bezzecchi then squeezing into 2nd.
All three are now quicker than Martin's FP1 time of a year ago.
Pedro Acosta was on course to top the timesheets... but runs wide at Turn 15.
Bagnaia returns to the Ducati garage and is heading back out.
Order at the halfway stage of the 45-minute FP1 session:
- Morbidelli
- Quartararo
- Vinales
- Martin
- di Giannantonio
- Bezzecchi
- Bastianini
- M.Marquez
- Acosta
- Oliveira
- Marini
- Nakagami
- R.Fernandez
- A.Espargaro
- A.Fernandez
- Miller
- A.Marquez
- Bagnaia
- Mir
- Binder
- Rins
- Zarco
Francesco Bagnaia walks out of the back of the Ducati garage.
Presumably, he doesn't feel the track is in a good enough condition to learn anything at the moment.
Mandalika is a big weekend for Yamaha, which needs to see if its impressive Misano speed can transfer over to a very different track.
The early signs at least are good, with Fabio Quartararo 2nd.
Team-mate Alex Rins - returning from sickness - is 21st, ahead of only Johann Zarco.
Red Bull KTM team manager Francesco Guidotti tells Simon Crafar that Jack Miller is reporting the circuit is really slippery, as expected.
Franco Morbidelli is now the fastest with a 1m 31.838s.
Maverick Vinales takes over at the top for Aprilia with a 1m 31.896s, using medium tyres front and rear.
Pertamina VR46, the adopted home MotoGP team this weekend, are not using their special red and white colours for practice but that's not slowing them down - Fabio di Giannantonio is now 2nd behind Martin, with Marco Bezzecchi in 3rd.
It's a steady start to the weekend for factory Ducati riders Enea Bastianini and Francesco Bagnaia, who are 13th and 19th after 6 laps.
There's a lot of expectation on Marc Marquez this weekend.
He never saw a chequered flag at Mandalika as a Honda rider, but the slippery track and stiffer Austrian-style rear tyre construction should play to his strengths.
Marquez is now 2nd fastest behind Martin with Maverick Vinales in third for Aprilia.