As the only chance to get prepared for all of the competitive sessions to come this weekend, a big queue formed at the end of the pitlane ahead of the 60-minute session getting underway.
The first time was set by AlphaTauri's Nyck de Vries, which established the leading benchmark at 1m49.541s.
De Vries and his team-mate Yuki Tsunoda were the only runners using the soft tyres from the off, with most of the rest on mediums while a handful began on hards.
The times tumbled quickly as the drivers got up to speed – Valtteri Bottas, Fernando Alonso, Lando Norris, Charles Leclerc and de Vries again having brief spells in the top spot, but it was the Red Bull pair that regularly leapt ahead as they pounded around on the mediums.
Verstappen had just brought the top time down to a 1m43.834s when the session was suspended at the end of the opening 15 minutes by a red flag.
This was caused by Kevin Magnussen stopping in the Turn 1 run-off with a loss of fuel pressure aboard his Haas just after he had had to turn out of a moment close to the wall on the inside of the 90-degree right and lost all his speed as he then went near the exit barrier on the other side of the track.
As he was stranded, the session was stopped, but the delay was made longer by Pierre Gasly's Alpine catching fire when he had gone slowly through the Turn 1 runoff well ahead of Magnussen, but then needing to stop inside Turn 12 at the track's castle section as the flames did not go out as he toured slowly back to the pits.
The fire, initially triggered by a hydraulic leak aboard the A523, blazed for several minutes before it was eventually brought under control, which ultimately meant the teams and drivers lost nearly a quarter of their total practice time as the session resumed with 32 minutes remaining.
The pack headed back out, minus Esteban Ocon in the other Alpine and the runners that had hit trouble, including Tsunoda, who had badly damaged the rear of his AlphaTauri returning to the pits with a puncture that caused him to spin at Turn 3.
All the remaining drivers continued on using the medium and hard tyres over the session's middle phase, with several putting in personal bests but not troubling Verstappen's top time.
The Red Bull pair appeared to be using this time to complete high-fuel preparation running ahead of the upcoming races, before coming in ahead of the final quarter along with most others, just as Lance Stroll split the leading pair with a flier on the mediums and Alonso reported a DRS issue aboard the other Aston.
The last phase became a mini-session on the softs as most of the drivers got their eyes in on the critical rubber for grand prix qualifying later on Friday, with Oscar Piastri leading the charge and jumping from 19th to seventh on the red-walled rubber.
Verstappen was the first of the frontrunners to set a lap on the softs, putting in a 1m43.042s that restored him to the top spot a few seconds after Alex Albon had forged ahead with a 1m43.628s aboard the slippery Williams.
But running a chunk further back on the track, Sergio Perez beat Verstappen in the opening two sectors and although he could not beat the Dutchman in the final sector he nevertheless moved into first place with a 1m42.651s.
Verstappen then slotted in a second run on the same set of softs that closed the gap to Perez before Leclerc split the two Red Bulls, despite the Ferrari driver having to abort his first flier going down the Turn 2 escape road but crucially without locking up.
Perez's second run came after two slow preparation tours and he put in a 1m42.600s to slip further ahead, until Leclerc's second qualifying simulation effort ended with the driver who has taken the last two poles in Baku going ahead on a 1m42.352s.
The action was not over even after the chequered flag came out as Verstappen had enough time for a third flying lap on his softs.
Although he ran adrift of Leclerc's time in the opening two sectors, the RB19's straight-line prowess meant he was able to gain enough to jump ahead and into what would remain as the session's leading time, a 1m42.315s.
Behind, Carlos Sainz, who had got away with glancing the inside wall at Turn 5 during the early running, completed his personal best lap on the softs and secured fourth, which was followed by Perez failing to go any quicker on his third late attempt.
In the final order then came Lando Norris, another driver to leap up the classification late on, followed by de Vries and Stroll.
Alonso ended up eighth but without a soft tyre run as Aston Martin opted to split its strategy, with the Spaniard also reporting a DRS issue ahead of the final runs but able to shake it off after repairs in the pits.
Albon ended up ninth ahead of Zhou Guanyu, while Tsunoda was able to make it back out late on after repairs to his car and take 14th.
The Mercedes drivers did not complete soft-tyre runs after both reporting brake problems during the opening laps.
Lewis Hamilton led the way for the squad in 11th, with George Russell 17th.
| Cla | Driver | Chassis | Engine | Laps | Time | Gap | |
|---|---|---|---|---|---|---|---|
| 1 |  Max Verstappen |
 |
Red Bull | Red Bull | 22 | 1'42.315 | |
| 2 |  Charles Leclerc |
 |
Ferrari | Ferrari | 21 | 1'42.352 | 0.037 |
| 3 |  Sergio Perez |
 |
Red Bull | Red Bull | 22 | 1'42.454 | 0.139 |
| 4 |  Carlos Sainz |
 |
Ferrari | Ferrari | 23 | 1'42.899 | 0.584 |
| 5 |  Lando Norris |
 |
McLaren | Mercedes | 22 | 1'43.125 | 0.810 |
| 6 | Nyck de Vries |
 |
AlphaTauri | Red Bull | 24 | 1'43.414 | 1.099 |
| 7 |  Lance Stroll |
 |
Aston Martin | Mercedes | 23 | 1'43.455 | 1.140 |
| 8 | Fernando Alonso |
 |
Aston Martin | Mercedes | 20 | 1'43.560 | 1.245 |
| 9 |  Alex Albon |
 |
Williams | Mercedes | 25 | 1'43.628 | 1.313 |
| 10 |  Zhou Guanyu |
 |
Alfa Romeo | Ferrari | 23 | 1'43.748 | 1.433 |
| 11 | Lewis Hamilton |
 |
Mercedes | Mercedes | 21 | 1'43.798 | 1.483 |
| 12 |  Oscar Piastri |
 |
McLaren | Mercedes | 23 | 1'43.980 | 1.665 |
| 13 |  Valtteri Bottas |
 |
Alfa Romeo | Ferrari | 23 | 1'44.010 | 1.695 |
| 14 |  Yuki Tsunoda |
 |
AlphaTauri | Red Bull | 18 | 1'44.137 | 1.822 |
| 15 |  Nico Hulkenberg |
 |
Haas | Ferrari | 21 | 1'44.323 | 2.008 |
| 16 |  Logan Sargeant |
 |
Williams | Mercedes | 16 | 1'44.900 | 2.585 |
| 17 | George Russell |
 |
Mercedes | Mercedes | 20 | 1'45.082 | 2.767 |
| 18 |  Esteban Ocon |
 |
Alpine | Renault | 8 | 1'45.955 | 3.640 |
| 19 | Pierre Gasly |
 |
Alpine | Renault | 7 | 1'46.321 | 4.006 |
| 20 |  Kevin Magnussen |
 |
Haas | Ferrari | 8 | 1'47.498 | 5.183 |
| View full results | |||||||
