A remarkable effort by Pierre Gasly put the AlphaTauri driver at the top of the timesheets in FP3 in Baku, the Frenchman clearing Red Bull's Sergio Perez by a comfortable margin of 0.344s.
The final practice session suffered several disruptions, the first of which was triggered by Max Verstappen when the Dutchman hit the wall at Turn 15 and was forced to retire his car on the spot, a mishap that dealt a blow to his qualifying preparations.
In the Mercedes camp, there was a glimmer of hope for Lewis Hamilton who set the third fastest lap overall, but teammate Valtteri Bottas could do no better than 13th, leaving the Brackley squad with another few hours of head scratching ahead of qualifying.
Air temperature in Baku was warm 27.5°C with track temps at 54°C when final practice kicked off, a crucial session for Mercedes to reset after its massive underperformance on Friday.
But Lewis Hamilton and Valtteri Bottas were in no hurry to hit the track as soon as the lights went green, contrary to Haas rookies Nikita Mazepin and Mick Schumacher who put the first times on the board.
As the track populated, drivers took turns at the top but AlphaTauri's Yuki Tsunoda lowered the benchmark to a 1m43.447s on the soft tyre, but the Japanese charger was outdone in short order by teammate Pierre Gasly while Charles Leclerc slotted into third.
Hamilton and Bottas eventually sprang into action, but the Briton appeared unimpressed with whatever changes had been made to his W12 overnight. "No rear end...or front," quipped the Mercedes driver over the radio.
But Red Bull's state of affairs was hardly better as a result of Verstappen making contact with the outside wall at Turn 15. Unable to engage reverse despite little apparent damage to the RB16B, the Dutchman exited his car, his session done and dusted.
Practice resumed with 25 minutes remaining on the clock, with Gasly leading the field with a 1m43.051s. Soft-tyre runs were the norm for most drivers, which allowed Aston Martin's Lance Stroll to enter the top four
A flyer by Carlos Sainz concluded prematurely at Turn 15 when the Spaniard ran down the escape road after braking late.
Radio communication in the Mercedes camp indicated that there was little change to the team's plight. "That change didn't make any difference, so I don't know," reported Bottas, sat down in 17th position.
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