After the early running, it was Sainz who led the way on a 1m 44.323s using medium tyres, a few hundredths clear of two-time Baku winner Perez on the same yellow-marked rubber, with Hamilton six-tenths back on the hard compound.
At the 20-minute mark, drivers began to make the switch to softs and, amid a flurry of qualifying-style laps, Sainz clocked a 1m 43.950s to maintain P1 over Oscar Piastri, Verstappen, Lance Stroll, Hamilton and Perez, while Haas super-sub Ollie Bearman sat in an eye-catching seventh.
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Lando Norris had been on course for a rapid lap until he encountered the slow-moving Pierre Gasly in the final sector, forcing the McLaren driver to back out of it while his Alpine rival got on the radio to apologise and report that he was trying to deal with battery issues.
Another attempt from Perez saw him take over at the top, the Mexican getting down to a 1m 43.490s, while replays showed moments for Verstappen, Sainz, rookie Franco Colapinto and Leclerc, who still seemed uncomfortable at the wheel after extensive checks in the Ferrari garage.
As the final push laps filtered through, Leclerc managed to put his problems to one side and charged to the top of the timesheets on a 1m 43.484s, slotting ahead of Perez, an improved effort from Hamilton, Sainz (who had another off at Turn 7), Piastri and Verstappen.
