Already on a tight schedule due to the decision to run both drivers on Wednesday, Williams programme was further hampered by an oil system problem which caused Nicholas Latifi to stop on track, thereby bringing about the second red flag of the day.

Desperate to put the nightmare of 2019 (and 2018) well and truly behind it, not to mention trying to re-establish itself as a serious player, engine issues last Thursday and Friday have cast a shadow over what was looking to be a strong start to the Grove outfit's year.

With her team completing the second lowest mileage of the opening week of testing, team boss, Claire Williams has admitted her frustration.

"We had some engine problems which have been a little frustrating," she said, according to Motorsport.com. "We're on our third engine issue now, which has obviously cost us quite a lot of track time, which is unfortunate.

"I suppose it is what can happen in testing," she continued, "and at least it's not our issue... that something has gone wrong with the car.

"Apart from that, it's gone well," she added. "We're covering the run programme as we can with the limited mileage that we've got, but I would be happier if we had some more miles under our belt I suppose.

"There were some other issues last week," she confirmed. "The one on Friday, (Mercedes is) still investigating, so you should talk to them about that.

"I don't think that they've found the problem," she admitted. "I think there was an issue with the MGU-H on the Thursday night one. There was a sensor issue on Friday morning that obviously was our issue. That put us off the track for probably half an hour, something like that. That's the only issue that we've had."

"The issue that Williams encountered today is different to the one they experienced last week," a Mercedes spokesman subsequently told Motorsport.com. "The first assessment points towards an oil pressure issue.

"The PU is now on its way to Brixworth where we will have the chance to take a more thorough look at it."

Check out our Thursday gallery from Barcelona, here.