Antonelli clocked a fastest time of 1:32.803 to top Thursday’s timesheets, outpacing Oscar Piastri’s McLaren by 0.0058 seconds.
A number of teams once again took the opportunity for a change of driver of the lunch break.
Antonelli took over from George Russell at Mercedes with Piastri in for Lando Norris at McLaren.
Nico Hulkenberg replaced Gabriel Bortoleto in the Audi as Sergio Perez took Valtteri Bottas’s place at Cadillac.
Verstappen clocked the fastest time of the day at that stage within the first 30 minutes of the afternoon session, recording a 1:33.444 to go 0.009s faster than Norris’s quickest time of Thursday morning’s running.
Antonelli was quickly up to speed too, going fourth with his first meaningful effort albeit a second off the pace of the Red Bull, with Hulkenberg going fifth at that stage.
Piastri was forced to take to the run off after catching a dramatic slide with the McLaren in the long right hander of Turn 13.
He breached the top 10 with his next effort, which placed him ninth and two seconds adrift of Verstappen.
Alonso brought out the red flags after 50 minutes after the Aston Martin driver stopped at the exit of Turn 4 with a loss of power, causing a delay of around 20 minutes as the AMR26 was recovered. Alonso did not return to the track for the rest of the day.
Honda confirmed to PlanetF1.com that the two-time world champion had suffered a power unit issue, with engineers looking into the details of the problem at the time of writing.
Alonso’s stoppage came as the latest blow to Aston Martin, which produced the only red flag of Wednesday’s running with Lance Stroll.
Antonelli improved his time within minutes of the resumption, moving up to third with a lap 0.431s off Verstappen’s benchmark.
Moments later, Verstappen improved his own time to 1:33.162 to extend his advantage as Piastri took third from Antonelli, lapping 0.462s slower than the Red Bull at that stage.
Hulkenberg was also improving, posting Audi’s fastest lap of testing so far with a time of 1:33.987. He stayed fifth.
Audi’s pace through the speed trap caught the eye with Hulkenberg and Bortoleto top of the list at 341km/h (211mph) and 337km/h (209mph) respectively.
Perez also made his first appearance of the day after a delay to Cadillac’s afternoon running, initially lapping faster only than teammate Bottas.
Piastri set a new fastest time of the day 100 minutes into the afternoon session, going 0.301s clear of Verstappen’s previous benchmark with a 1:32.861 on the same C3 tyre.
Ocon was another to post his personal best lap of the day as the two-hour mark approached, but remained on the margins of the top 10 at that point with Haas prioritising long running.
Hamilton, whose morning running was limited to five laps due to an issue with his Ferrari, had a big slide and took a trip through the gravel on the exit of Turn 4.
The seven-time world champion spent most of the afternoon session carried out long runs before being briefly sidelined with what appeared to be an issue with the rear brakes.
Colapinto improved to seventh with around 90 minutes left on the clock.
As darkness descended, Antonelli posted a new fastest lap of the day with 55 minutes remaining, lodging a 1:32.803 on the C3 tyres to go 0.058s quicker than Piastri.
Hamilton re-emerged on the C3 tyres but blew his first push lap by locking up and taking to the run-off area at the Turn 8 hairpin.
Personal bests in the first and second sectors saw Hamilton rise to fifth, but a rather scrappy effort saw him trail Antonelli by 1.125s.
Lawson, Perez, Ocon and Albon (using the C5 tyre on the Williams) also improved as more drivers turned to performance running in the closing stages of the afternoon.
Perez also turned to the C5 tyre with 30 minutes left on the clock and found himself improving to 14th, albeit 0.814s off Albon’s time on the same rubber.
Colapinto also used the C5s to put the Alppine sixth, seven tenths faster than fellow Mercedes customer Albon.
Hamilton tried again on the C3s, but made a mistake and ran wide at the final corner after posting two green sectors. He opted against finishing the lap and returned to the pits.
Lawson also had a wide moment at the esses, taking to the run-off area and running through the gravel on one of his laps.
The day concluded with a third trial of the revised start procedure being proposed for the F1 2026 season.
A prolonged start procedure is thought to be required given the high turbo lag – a function of the MGU-H being removed from the engine architecture – with the 2026 cars.
Piastri’s car came to a halt as he led the field out of the pit lane ahead of the start. He managed to get his McLaren going again to take his place on the grid.
F1 Testing: Bahrain Test 2, Day 2:
1 Kimi Antonelli Mercedes 1:32.803 – 79 laps
2 Oscar Piastri McLaren +0.058 – 86 laps
3 Max Verstappen Red Bull +0.359 – 139 laps
4 Lewis Hamilton Ferrari +0.605 – 78 laps
5 Lando Norris McLaren +0.650 – 72 laps
6 Franco Colapinto Alpine +1.015 – 120 laps
7 Nico Hulkenberg Audi +1.184 – 73 laps
8 George Russell Mercedes +1.308 – 77 laps
9 Esteban Ocon Haas +1.398 – 58 laps
10 Liam Lawson Racing Bulls +1.729 – 106 laps
11 Alexander Albon Williams +1.752 – 117 laps
12 Gabriel Bortoleto Audi +2.460 – 29 laps
13 Oliver Bearman Haas +2.476 – 69 laps
14 Sergio Perez Cadillac +2.566 – 50 laps
15 Fernando Alonso Aston Martin +4.669 – 68 laps
16 Valtteri Bottas Cadillac +7.390 – 58 laps
