AlphaTauri racer Gasly had used the cooler conditions as dusk arrived over the Sakhir circuit late into the four-hour afternoon session to bolt to the top of the timing screens.
Equipped with the softest C5 compound Pirelli tyre, Gasly overcame the gusty Gulf air to post a 1m33.902s to sit half a second clear at the top over the two Ferraris.
