Perez‘s 1:32.758 in the middle of the session couldn’t be bettered with Alonso trailing by 0.438 seconds, with reigning champion Max Verstappen a further 0.179 seconds adrift.
Interestingly, Perez was quickest on the C2 medium and C3 soft tyre runs, although FP1 in Sakhir is usually unrepresentative of the true pace because it is held in the day, when qualifying and the race is at night.
Lando Norris was fourth for McLaren in front of Charles Leclerc, who set his fastest time on the medium tyres and was 1.499 seconds behind Perez.
Lance Stroll badly needed track time after missing pre-season testing due to a wrist injury, but only completed two laps in the opening 35 minutes due to an ignition issue. However, he managed to get himself up into sixth with five minutes remaining.
Kevin Magnussen was seventh, with the Alfa Romeo pair of Zhou Guanyu and Valtteri Bottas in eighth and ninth.
Lewis Hamilton and George Russell were 10th and 11th but didn’t set a fast run on the soft tyres.
Carlos Sainz was last after having a big spin as he went over the bumps at Turns 9 and 10, flatspotting his medium tyres as Ferrari trialled different rear wings early in the session.
Elsewhere, Oscar Piastri was 12th on his first FP1 as a full-time F1 driver, with Yuki Tsunoda, Nico Hulkenberg, Esteban Ocon, Nyck de Vries and Pierre Gasly in behind.
Williams appear to be at the back as Logan Sargeant was 18th and Alex Albon was 19th.
An unrepresentative session
The Bahrain GP takes place at night which makes FP1 largely unrepresentative as to what the pecking order actually is.
In pre-season testing, Perez set the fastest time of a 1:30.305 but he was 2.453 seconds behind that in the opening practice session in Sakhir.
It was also interesting to note that nearly everyone avoided the C1 hard tyre compound, as the teams want to save at least two sets of that tyre for Sunday’s race.
Pirelli made changes to the C1 compound over the winter to bring it closer to the C2 after it was hardly used in 2022.
They have definitely done this, so much so, that the C1 now appears to be favoured over the C2, at least in Bahrain.