Aleix Espargaro produced a late flash of brilliance to set a lap record for the Indonesia MotoGP at Friday's crash-marred second practice, in which championship leader Francesco Bagnaia finished outside the top 10.
The Aprilia rider coped with the hot and humid conditions to snatch a lap record of one minute 30.474secs from VR46-Ducati rider Marco Bezzecchi, who had broken the record himself despite an earlier crash a week after surgery for a broken collarbone.
The Spaniard's lap -- which came before a crash -- was nearly two-tenths of a second clear of teammate Maverick Vinales in second and Bezzecchi in third.
Jorge Martin, who sits second in the overall standings, was 0.400sec back in fifth but he outgunned his championship rival Bagnaia.
The championship leader never got going and the Italian finished more than a second back in 16th.
Martin's pace will be of concern to the reigning champion, with just three points separating them heading into Saturday's sprint race and the main event on Sunday.
The second session was filled with crashes, with Augusto Fernandez and Brad Binder colliding just several laps in, while Jack Miller crashed twice.
In the first practice session, Martin secured the fastest time, again showing his pace over Bagnaia, who was 0.759sec back in sixth.
Marco Bezzecchi, third in the standings, crashed in the first session but still finished fifth, 0.741sec behind Martin.
The top 10 from practice are joined as usual by the fastest two riders from the first qualifying run on Saturday, to determine the first four rows of the grid for both Saturday's sprint race and Sunday's main event.
Indonesia is hosting the 15th of the 20 MotoGP races this season.
Top 10 times from the first practice session at the Indonesia MotoGP:
1. Jorge Martin (ESP/Pramac Ducati) 1 min, 31.811sec, 2. Maverick Vinales (ESP/Aprilia) at 0.102sec 3. Aleix Espargaro (ESP/Aprilia) 0.536, 4. Franco Morbidelli (ITA/Yamaha) 0.730, 5. Marco Bezzecchi (ITA/Ducati-VR46) 0.741, 6. Francesco Bagnaia (ITA/Ducati) 0.759, 7. Jack Miller (AUS/Red Bull KTM) 0.835, 8. Brad Binder (SAF/Red Bull KTM) 0.857, 9. Enea Bastianini (ITA/Ducati) 0.952, 10. Luca Marini (ITA/Ducati-VR46) 1.000sec
Top 10 times from the second practice session at the Indonesia MotoGP:
1. Aleix Espargaro (ESP/Aprilia) 1 min, 30.474sec, 2. Maverick Vinales (ESP/Aprilia) at 0.154, 3. Marco Bezzecchi (ITA/Ducati-VR46) 0.170, 4. Brad Binder (SAF/Red Bull KTM) 0.288, 5. Jorge Martin (ESP/Pramac Ducati) 0.400, 6. Marc Marquez (ESP/Honda) 0.632 , 7. Miguel Oliveira (POR/RNF) 0.725, 8. Fabio Di Giannantonio (ITA/Gresini) 0.733, 9. Jack Miller (AUS/Red Bull KTM) 0.742, 10. Fabio Quartararo (FRA/Yamaha) 0.755