Robert Kubica made the call to sit out Friday's final day of pre-season testing at the Circuit de Barcelona-Catalunya, in order to give Lance Stroll more time in the car.
The Williams reserve and development driver had been scheduled to be in the FW41 for this afternoon's session. However, he volunteered to step aside in favour of Stroll.
"It was actually under Robert's instigation," deputy team principal Claire Williams said. "He knows that for the team's benefit, the race drivers need the maximum amount of mileage."
"Robert is an incredibly considerate racing driver," she continued. "We're very lucky in that.
All teams have lost running time during the two weeks of testing because of the weather as well as sundry reliability issues.
"It was his generous offer yesterday [to step out]," said Williams. "It was Robert, it was off his own bat
"It wasn't the team. We haven't asked him. It wasn't Lance, Lance didn't ask him.
"Clearly we were going to accept that we need that our race drivers to be in a best possible position that they can be going to Australia. And having them both in the car today will help us."
“I said I had no problem [about giving up the time],” Kubica said of his decision. “I just made sure the team decided what is best.
"I don’t think I have done anything strange but people are asking me as if I have given away my heart!
“I’m not paid to be a race driver," he added. "I’m not scoring the points for the team so I don’t see it as so strange. It looks like it’s very strange, probably people are not used to it."
"But it shows we are working in one direction and with one goal, which is to use our chances and to maximise our possibilities for results."
The team's technical director Paddy Lowe said that the driver schedule had always been planned with changes in mind.
“Being open with you, we always put some of Robert’s half days at the end so that we would have flexibility," he said. "The priority was for the race drivers to be prepared for Australia,” said Lowe.
“What was really nice was that Robert volunteered himself before anyone needed to have any discussions about any re-balancing.
Kubica had been hoping to be one of the team's full time drivers in 2018. However he lost out to Russian rookie Sergey Sirotkin, who was be at the wheel of the car on Friday morning.
The Pole is still hoping that doing a solid job for the team this year will put in him the running for a return to Formula 1 next season.
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