Leclerc, who has yet to finish an F1 or FIA Formula 2 race at Monaco, had to abort a couple of potentially even faster laps late on. But his 1m14.531s posted on medium tyres kept him at the top of the timing screens, despite the late improvement from Perez.
Defending champion and new points leader Max Verstappen, meanwhile, ran in fourth as the Mercedes contended with further porpoising trouble aboard the W13.
