Quartaro has not won a race since Silverstone 2021 last August, but he beat polemic Joan Mir on the fourth lap and took the first decisive victory in a difficult season so far.
Mir stepped off the streak from second on the grid to lead the race for the first time since his title-winning season in 2020, while Quartaro jumped from fifth to third.
Between the two champions was Bramack Pullman Johann Zarco, but Quartararo stole second from him in Turn 3 right as Mir pulled about six tenths up front.
Zarco was briefly pushed back to fifth by his Ducati factory counterpart Jack Miller and Alex Marquez’s LCR Honda – although Zarco quickly returned to the podiums by the end of round two.
Quartararo took up Mir’s lead on lap two and quickly came close, with the Yamaha rider moving into Turn 1 in Round 4 after pulling off a sweeping final turn and taking a profit from a Suzuki pull.
Quartararo immediately opened up a close-of-second lead and would continue to extend that as Mir once again fell into the clutches of Zarco.
Zarco made an unsuccessful attempt to take second from Mir at the start of lap 16, the Pramac rider running into the first corner.
But he did pass the pass next time, now forcing Mir to defend Miller to finish last on the podium.
Miller was running on Mir in the first corner when he started on lap 19 of 25, but he would miss the front of the Ducati under braking and wipe out the Suzuki rider.
The direction of the race put the accident under investigation.
This upgraded Aprilia’s Alex Espargaro to third, with the Argentine winner engaging early in a fight with Alex Marquez, KTM’s Miguel Oliveira and hardcore Alex Rins on a factory second Suzuki.
Reigns qualified 23rd after making a strategic blunder in a wet-to-dry Q1 session, but on the opening lap he climbed to 11th and made his way through the bottom half of the top 10.
On lap eight, Reigns picked Oliveira’s Jeep in Turn 10 and went around the outside of Alex Marquez in Turn 10 to move into fifth.
Up front, Quartararo dominated the pace and was able to move by more than six seconds past Zarco in one stage as he went without problems to the checkered flag to claim his first victory in his title defense.
Zarco would be threatened by Alex Espargaro during the final laps, but held out to secure his second podium in 2022 ahead of the Aprilia rider.
Rins’ amazing rescue mission led him to fourth place and put him level on points with Quartararo at the top of the standings (although the latter is ahead by virtue of his victory).
Both riders scored eight points, eight ahead of former leader Bastianini, who crashed on lap 10 after battling for the edge of the top 10.
Home champion Miguel Oliveira completed the top five on his Factory KTM, while teammate Brad Bender crashed.
Marc Marquez beat his brother Alex Marquez on a Honda LCR by 0.020 seconds after the pair engaged in a heated battle with sixth in the closing stages.
The six-time world champion had a similar tight battle with teammate Paul Espargaro in the early stages, but went out ahead, while the latter was back in ninth behind Francesco Bagnaia on a Ducati – the pair were touching on the last lap of turn 9.
Bagnaia was cleared from the race this morning after a major crash in qualifying left him on the grid.
The top ten was completed by Maverick Viñales in April, with Andrea Dovizioso of RNF Racing, Luca Marini rider VR46 Ducati, Franco Morbidelli of Yamaha, Remy Gardner Tech 3 KTM rookie, and Marco Besicci’s VR46 sister bike taking the final points .
A crash left him for Takaaki Nakagami in 16th place ahead of rookie RNF player Darryn Binder, while Aprilia wildcard player Lorenzo Savadori, Fabio Di Giannantonio of Gresini and Jorge Martin of Pramac failed to make the checkered flag.