Ferrari's Charles Leclerc pulled off to the side of the track at turn 19 with less than twenty minutes into the session, reporting an issue with the engine, Leclerc out on only his first lap of the session.
His teammate Vettel suffered having a lap time deleted for going wide at turn 19, where Mercedes' Bottas was lucky to not endure the same fate as the team warned him that we was triggering the timing loop and to be careful of going over the line.
Verstappen turned his first laps of the day halfway through the session and instantly took second in the standings, showing some confidence pace within the RB15 coming into qualifying, eventually topping Vettel for top spot.
McLaren's Norris set a blistering lap to go within half a second of Verstappen with a handful of minutes to go in the session, giving the team some positivity going into the qualifying session.
Bahrain International Circuit - Winter testing