Sergio Perez's fine form at the Baku City Circuit continued with the fastest lap in final practice.
Last year's Azerbaijan Grand Prix winner had been fastest in FP1 before Charles Leclerc hit back in the second session but as temperatures cooled, Perez posted a lap of one minute 43.170secs, 0.070s faster than the Ferrari driver.
Max Verstappen finished third but had his first timed run disrupted by yellow flags following Valtteri Bottas' off-track excursion at turn three in the best of the conditions.
Carlos Sainz was four-tenths slower than Perez ahead of both McLarens, who enjoyed a much more positive hour of running.
The start of the session was delayed by 15 minutes whilst circuit officials repaired the Tecpro barrier at turn one after a four-car incident at the end of the preceding F2 race.
With track temperatures much higher than what would be expected as the sun sets in qualifying, teams waited until the very end of the session before posting their representative times.
Traffic was also highlighted as an issue ahead of qualifying with Verstappen impeded on his final timed lap.
Leclerc also failed to complete his final flying lap after locking up into turn 15, forcing him to bail out and take to the escape road.
Lando Norris ended the session 1.2s adrift of Perez, with team-mate Daniel Ricciardo crucially within half-a-tenth of his team-mate to provide optimism amidst the scrutiny surrounding the Australian.
Pierre Gasly finished seventh for AlphaTauri, with a time near-identical to Ricciardo to set up a tantalising battle for the best-of-the-rest positions.
Mercedes played their strategic hand early ahead of the grand prix by scrubbing up a new set of hard tyres in preparation for the race.
But whilst the team seemingly eased some of the violent bouncing that plagued its Friday running - the fitting of its Barcelona-spec floor no doubt helping - both drivers struggled with the rear of the car.
George Russell again was the lead Silver Arrow, finishing a tenth-of-a-second adrift of Gasly but two-tenths - and four places - ahead of Lewis Hamilton.
Esteban Ocon and Sebastian Vettel rounded out the top 10 for Alpine and Aston Martin.
Azerbaijan Grand Prix final practice results
1. Sergio Perez [Red Bull] 1:43.170
2. Charles Leclerc [Ferrari] +0.070s
3. Max Verstappen [Red Bull] +0.279s
4. Carlos Sainz [Ferrari] +0.426
5. Lando Norris [McLaren] +1.248s
6. Daniel Ricciardo [McLaren] +1.306s
7. Pierre Gasly [AlphaTauri] +1.321s
8. George Russell [Mercedes] +1.403s
9. Esteban Ocon [Alpine] +1.515s
10. Sebastian Vettel [Aston Martin] +1.519s
11. Fernando Alonso [Alpine] +1.672s
12. Lewis Hamilton [Mercedes] +1.675s
13. Lance Stroll [Aston Martin] +1.709s
14. Zhou Guanyu [Alfa Romeo] +1.743s
15. Kevin Magnussen [Haas] +1.749s
16. Yuki Tsunoda [AlphaTauri] +1.794s
17. Alex Albon [Williams] +2.309s
18. Mick Schumacher [Haas] +2.362s
19. Valtteri Bottas [Alfa Romeo] +2.404s
20. Nicholas Latifi [Williams] +2.900s