Valtteri Bottas topped the timesheets at the end of a chilly Tuesday morning at the Circuit de Catalunya.
Indeed, such were the conditions, the track slippery and wet following overnight snow which left the circuit damp, the decision was taken early on to forgo the lunch break in order that teams could get in as much running as possible.
All that changed just after midday (local time), once Bottas had posted a 20.806, Stoffel Vandoorne responding with a 21.202 and then a 20.325, albeit on hypersofts, the first time they have been used this week.
Soon more drivers were on track and trading times, Vettel improving to third ahead of Sainz and Sirotkin.
After topping the timesheets and the mileage yesterday, it was back down to earth for Red Bull, Max Verstappen sidelined for the morning by what is thought to be a fuel system issue. Indeed, having completed an installation lap earlier it was only at 12:56 that he reappeared again.
While fans who were expecting to take advantage of the pitlane tour will be disappointed by the fact that this has now been cancelled, they are at least guaranteed some fun and games over the next few hours as the teams make up for this morning's lost running.
Indeed, even as we type up this report, Verstappen has posted his first time of the day (33.930), while Pierre Gasly has improved to fourth (21.318).
With further rain and snow expected over the next couple of day, there has been talk of extending the test until Friday. However, other than needing the agreement of all the teams - which is never easy - Williams has the track booked for Friday for a filming day. As a result it is now understood that instead next week's test could be extended by a day.