Despite light rain before the session, the track filled up right at the beginning of FP2.
However, Takaaki Nakagami’s session was interrupted at the start of his first flying lap when he suffered a terrible fall over the top of the hill on the descent to Turn 1.
The LCR driver was taken to the medical control center where he was found to have escaped a serious injury and was back in action in the final 10 minutes of the session.
World champion Joan Mir set the early pace on his Suzuki with 1: 41.809 minutes before Fabio Quartararo of Yamaha started the first of his stints at the top of the timesheet with 1: 41.309 minutes 32 minutes before the end.
The top position changed hands several times in the next 15 minutes, with Ducati’s Francesco Bagnaia being the first to defeat Quartararo with 1: 41.052 minutes.
Last year’s Portuguese winner, Miguel Oliveira, led his KTM to 1: 41.038s nine minutes later, before Alex Rins lowered the benchmark on his Suzuki to 1: 41.020s a few moments later.
Quartararo broke the 1:41 mark about a minute after Rins hit the top.
Aprilia’s Aleix Espargaro made the first headline lap on a fresh, soft slick with 11 minutes to go. The Spaniard was 1: 40.907 minutes ahead of Quartararo.
This was compromised in the last seven minutes as the rest of the field tried their time attack attempts.
Oliveira improved it with his first attack attempt of 1: 40.703 minutes before Mir broadened the field with 1: 40.285s.
Mir’s run at the front lasted only a moment when Bagnaia flashed the field with a 1: 39.866 on his Ducati.
Quartararo managed to narrow his deficit on his final lap but fell 0.038 seconds short – despite that lap being canceled for a yellow flag violation, with Bagnaia’s lead increasing to 0.340 seconds.
I completed the top three in front of Suzuki team-mate Alex Rins, while Jack Miller on the second works team Ducati was fifth.
Marc Marquez was out of shape in 1: 40.339 minutes at the end of his first day, 0.473 seconds off pace in sixth place after a wild final lap of his Honda on its way into the right-hand turn of Turn 8 en route to shooting lagged back on a MotoGP bike in a provisional Q2 place in nine months.
Maverick Vinales finished seventh on his Yamaha, World Championship leader Johann Zarco finished eighth, although his Pramac Ducati went up in flames after the checkered flag when attempting to start training.
The top 10 were completed by Oliveira and Nakagami, who heroically took the lead of LCR teammate Alex Marquez with 1: 40.611 minutes.
Pol Espargaro only finished 12th on his factory Honda while Aleix Espargaro slipped to 14th after a late accident at Turn 11.
Doha GP Podium and Poleman Jorge Martin (Pramac) was last 3.055 seconds behind the pace, while Petronas SRT’s Franco Morbidelli finished 19th after apparently opting not to start a time attack late.