Robert Kubica sacrificed final test for Lance Stroll

Hypersoft tyres making their mark at testing (2:45)

ESPN's Nate Saunders and Laurence Edmondson discuss the surprising track times set by teams on the hypersoft tyres from yesterday's testings and what can be expected on the final day. (2:45)

MONTMELO, Spain -- Robert Kubica says he willingly gave up his final pre-season test appearance to Williams race driver Lane Stroll in order to strengthen the team's Australian Grand Prix chances.

Kubica, Williams' reserve driver, was slated to take over from Russian rookie Sergey Sirotkin on Friday afternoon. However, that plan was confirmed to have changed in the morning, with Sirotkin's teammate Stroll given a final afternoon in the car before the opening race at Melbourne.

Teams lost a significant chunk of running to adverse weather conditions last week and Williams is one of only two teams to have given up track time to a non-race driver -- Force India ran Nikita Mazepin during the first test. Speaking at midday, team boss Claire Williams insisted the decision to let Stroll have another run had been Kubica's.

"It was actually under Robert's instigation," she said. "He was due to run this morning but over the course of the seven days we've had here the race drivers over various different reasons whether it is the weather or directions we've taken it means they haven't had the track time they needed in time for Australia.

"As everyone knows Robert is an incredibly considerate racing driver and we are very lucky in that and he knows for the team's benefit the race drivers need the maximum amount of mileage so it was his generous offer yesterday. It wasn't the team, we didn't ask him, we didn't ask Lance and Lance didn't ask him, it was Robert and off his own back. Clearly we're going to accept that as we need our race drivers to be in the best possible position they can be in for Australia so having them both in the car today will help us get to that point."

At his own session with print and online media in the afternoon, Kubica admitted he was surprised by the attention given to the last-minute change.

"I don't think I have done anything strange but it looks like, people are asking me as if I have given away my heart!" he joked after one question about the decision.

He then pointed out the terms of his contract with Williams, which state he is a reserve driver rather than one signed up to contest all 21 races.

"I'm not paid to be a race driver. In my wording for this year there is no race driver under my name."

When asked who had made the initial suggestion he give up the session, Kubica said: "Well, what's the difference? It comes from me. I say that I have no problem to give away the time if the race drivers feel they need more time.

"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. And that's it."