Without even starting a flying lap, reigning MotoGP champion Fabio Quartararo had a moment heading towards turn seven. The Yamaha rider crossed a wet patch which resulted in the rear momentarily coming around.
Looking to carry on his form from the opening session, Alex Marquez got straight down to business as he set a 1:46.569s – eight tenths clear of Pol Espargaro.
After setting a lap time nine tenths better than his current provisional pole effort, Marquez was bumped down to third as Joan Mir and Jack Miller went quicker.
Marquez then went 1.3 seconds quicker than Mir on his third flying lap, before brother Marc made it a Marquez 1-2.
While Mir, Miller and Quartararo all got close to A. Marquez, the LCR Honda rider improved by a further five tenths in what looked like an untouchable time.
However, Pramac rider Johann Zarco produced a stunning effort out of nowhere to go even better.
After losing provisional pole to Mir, Zarco showed no signs of playing second best, quite the opposite as he went top by five tenths. The same margin that he was beaten by Miller just seconds later.
A. Marquez made it two Honda riders to crash in Q2 after going down on the cooldown lap.
Yellow flags cost Marc Marquez a potential pole position
Not to be outshone by his brother or any other rider for that matter, M. Marquez looked to have pole position in the bag, however, his top time was set under yellow flags and therefore deleted, as was Quartararo’s time after the Frenchman went P2 .
The yellow flags were deployed due to P. Espargaro crashing at the final corner. With the track now back to green flag conditions, Mir looked to have secured his first MotoGP pole before Zarco pipped him as the checkered flag dropped.
Aleix Espargaro, who was absolutely nowhere all session, managed to claim third with his last lap around.
Garnder and Bagnaia suffer big highsides as early dry tire gamble backfires in Portimao MotoGP Q1
Despite the bright sunshine beginning to dry the Portimao circuit, wet tires were the option to be on.
However, Takaaki Nakagami and rookie Remy Gardner made a bold move to head out on dry tires, which immediately proved to be the wrong call as Gardner suffered a highside on the entry to turn nine.
Not to be deterred by that, Ducati rider Francesco Bagnaia left pit lane also on dry tires as he attempted to make it through to Q2.
But like Gardner, Bagnaia suffered a big highside (turn two) as lessons from what happened to the Tech 3 KTM rider were clearly not being learned. Slow to his feet, Bagnaia was then seen sitting trackside and getting a medical check-up.
Looking to make it a successful Q1 for LCR Honda, A. Marquez was leading the way from Nakagami with just two minutes remaining.
And although a lull in almost laps seemed to indicate track conditions were past their best, Andrea Dovizioso blasted to the top by over seven tenths.
With the final sector now bone-dry, lap times began improving drastically. Marquez dislodged Dovizioso at the top before Martin knocked the Italian out of the top two.
A late crash for Enea Bastianini resulted in the championship leader failing to advance, while Luca Marini had no such issues as he delivered a brilliant final effort to make it through with Marquez.
Another session hugely dominated by crashes which has been a theme all weekend in Portimao.