The start of the fourth day of testing at Barcelona was a wet one, with the snow from Wednesday still providing a lot of humidity and puddles all over the circuit. With temperatures on the rise though, running was indeed possible, and useful for the F1 teams.
Due to the early conditions, only few drivers went out on track in the first few hours. Stoffel Vandoorne was mostly the only man out on track as McLaren seemed to maximise its track time following time losses on Monday and Tuesday.
Marcus Ericsson joined the party as well, but when he started his 12th lap, he got himself caught in the gravel trap, creating a red flag situation that stopped his running for a good half hour until his team got the car cleaned up again.
Towards 11:00 local time, drivers started switching to intermediate tyres, which was the sign for many teams to also take the opportunity to complete a few more laps. Bottas and Vettel for instance were as such involved in an interesting battle at the top of the timesheet, as each of them improved lap after lap, continuously changing the timesheet until Bottas slashed another 2 seconds off his best to settle that fight on inters.
Times steadily improved throughout the morning, from Vandoorne's first timed lap of 1:59 until 1:25 from Nico Hulkenberg on softs. Only 10 minutes before that, Bottas had been the first to switch to slick tyres, opting for the medium compound himself.