From the outset, the Grove outfit has made clear that the Pole's outings this week are not about lap times or even the amount of laps completed, rather Kubica's ability to adapt to contemporary F1 cars and perform at the highest level just seven years after almost losing his arm.
This afternoon, the Pole will get to try Pirelli's softer 2018 compound, having been eighth fastest yesterday on softs, while his rivals' best times were posted on the new Hypersoft.
Speaking at the end of yesterday's session, Williams technical chief Paddy Lowe was clearly impressed, though it is likely to be several weeks before a decision is announced.
"Robert did a great job," he told reporters. "We were very happy with the number of laps and with the running altogether.
"His feedback is very good," he continued. "He is a driver of tremendous experience and very knowledgeable around his work. His job is professional racing driver, so he has that confidence... and you can feel it in the garage, everybody's happy.
"Robert is a driver that we've all admired when he drove in Formula One and even since then. It's a great example of his character that he considered coming back from that accident that he has been fighting away, seeing if he could come back into Formula One."
With Kubica having firmly denied claims that he is driving one-handed, but admitted to having to had to adapt to F1 again, Lowe was asked if he, and the team, have any doubts in terms of the Pole's fitness. "There are no issues around that subject," he immediately replied."
When asked what the next step might be, the Briton replied: "I'm not talking about steps. We are testing and understanding tyres on the car and Robert is a fantastic driver to contribute to that process.
"We're concentrating on the testing at present, then we'll regroup afterwards to make our decision for next year in terms of racing."
Check out our Wednesday gallery from Yas Marina, here.