Why Williams is interested in Kubica

As the pieces continue to fall into place to form next year's Formula 1 grid, a seat at Williams has become the most sought after.

Lance Stroll's place in the team for 2018 is assured, but it remains unclear who will be racing alongside him.

Autosport understands Williams has slimmed its options down to three - retain Felipe Massa for another year, promote Paul di Resta from reserve driver or, as it emerged in Singapore, give Robert Kubica his return to F1.

Kubica's F1 career stalled after he suffered life threatening injuries in a rally crash in 2011. He injured his right arm, and required several surgeries and was left with limited movement in it. The chances of a return looked slim.

But earlier this year, he began his push to return to grand prix racing next season by testing for Renault, which admitted it was evaluating Kubica for a race seat in 2018 alongside Nico Hulkenberg.

"We don't have all the answers that we wanted, and F1 is very restrictive in terms of testing" Cyril Abiteboul on Renault's evaluation of Robert Kubica

Kubica's former team gave him a private test in a 2012-spec Lotus - a car that he was familiar with - at Valencia and followed that up with a full-day in the post-Hungarian Grand Prix in-season test.

An assessment of how he performed in those tests varies depending on who you speak to, but ultimately, Renault decided not to pursue it.

You could read that as Renault feeling Kubica was not ready to return to F1, but on the other hand, you could argue it wanted to do more testing but ran out of time.

Speaking at Spa, Renault managing director Cyril Abiteboul said he would ideally like to test Kubica again but in-season restrictions meant there was no chance of running him outside of a race weekend.

A Friday practice outing at a grand prix would be the only chance, but that would not provide the ideal conditions for Renault to continue evaluating Kubica.

"We said we wanted to be extremely methodological and analytic about the way that we were approaching things with Robert," explained Abiteboul in August.

"It was not a PR exercise, it is something that we are taking very seriously and we are trying to leave the emotions on the side.

"We don't have all the answers that we potentially wanted to get from the test, and in addition to that F1 is very restrictive in terms of tests you can do.

"In a perfect world we would want to do more of this type of test to see if he can race again at the level that he and we could have wanted."

Renault was unsure whether Kubica could cope with racing scenarios - such as changing weather and first corner incidents, having not experienced them for some time.

"Testing in isolation, a private test, one car, in control of the run, without rain, without first-lap action - all of that needs to be factored into the decision of pursuing or not pursuing," added Abiteboul.

The situation became more complicated when Carlos Sainz Jr, a driver Renault has been chasing since last year, became available over the summer, as part of the McLaren-Renault/Toro Rosso-Honda engine swap deals.

In order for McLaren to part ways with Honda, it needed Toro Rosso to agree to give up its supply of Renault engines and therefore free it up for McLaren.

Renault agreed to the termination of the Toro Rosso-Renault deal, but only on the proviso it could sign Sainz. Red Bull agreed to a one-year loan with an option to recall him for 2019.

It all happened reasonably quickly and Renault had to react, which in turn meant it no longer had a seat for Kubica, even if it believed further testing could prove he was ready for a return.

So it makes complete sense that Williams, a team in the market for a top-line driver to partner Stroll in a bid to prove it belongs at the sharp end of the field, would offer Kubica a potential lifeline by attempting to complete the evaluation.

It already has a programme in place where it can give Kubica the mileage required to fully understand whether he can drive at race pace consistently over a grand prix distance.

The team has a 2014-spec car, which it used to get Stroll up to speed ahead of his debut and help him learn the grand prix circuits he would be racing on this season.

"The fact Kubica now believes in himself will play a role in Williams's decision-making"

It is believed Williams is preparing to run Kubica in a test behind closed doors at a European circuit in the coming weeks, with funding for the programme understood to come from a Polish oil company.

That would allow Kubica to get more experience in a V6 hybrid car and build up critical mileage in modern F1 machinery.

The tests are by no means proof that he will ultimately get the drive, but at least they can help answer the question of whether Kubica has the capacity to return to F1.

When interviewed by this writer for the BBC in late 2013, Kubica said it was his dream to return to F1, but admitted it was "nearly impossible".

But since then, he has undergone a series of operations and rehabilitation, spent time in simulators, tested a Formula E car, competed in rallies and run in sportscars and one-make GT cars. And his view has changed.

He believes there is a chance of an F1 return, hence why he bolstered his management team recently with the signing of reigning world champion Nico Rosberg to specifically focus on a return in 2018.

The fact Kubica now believes in himself will be a factor in Williams's decision-making, but more important is that it does its due diligence and ensures that, beyond doubt, he is capable of returning.

It cannot risk putting him in the car if it does not believe it is safe to do so.

Williams is woefully short of driver options and the person in its second seat ideally needs to be over 25 years old as part of its arrangement with title sponsor alcohol brand Martini.

It is believed there could be some wriggle room to get around that issue, but Williams does not want to rock the boat unnecessarily with a key sponsor it has worked with since 2014.

For now, that rules out Mercedes junior Pascal Wehrlein, 23 next month, while it is understood Williams is not interested in recruiting Jolyon Palmer after he lost his seat at Renault.

Though Marcus Ericsson has made enquiries about a drive, a move for the current Sauber driver is thought highly unlikely.

Williams tested the water with Fernando Alonso, but it would have found it almost impossible to match his salary demands and he is set to re-sign for McLaren now it has parted ways with Honda.

Other target Sergio Perez decided he could not risk leaving Force India for Williams given its current form and knows a good season in 2018 is important given several seats at the big teams will be available for '19.

That leaves Williams with two options beyond Kubica.

First there is di Resta, who pushed himself into the frame after a strong performance as a stand-in for Massa in Hungary. The team was impressed with the way he drove that weekend, particularly given the lack of notice and experience with the new generation of cars.

Then there is Massa, a driver Williams holds in high regard, particularly after he helped it out of a hole when Mercedes poached Valtteri Bottas, and who has scored points consistently this year.

Williams wants to deal with the driver situation sensitively and is keen to avoid destabilising Massa for the rest of the season, particularly as running him again is a distinct possibility if the Kubica test doesn't work out.

Fortunately, it is in no rush to make a decision on its line-up as it is under no pressure to do so. If Kubica does not work out, Massa has said it is Williams or nothing for 2018 while di Resta is not in demand for a seat elsewhere.

Williams therefore has the luxury of time to fully evaluate Kubica - something Renault did not have. It has nothing to lose by giving Kubica a chance.

If the series of tests prove a return isn't possible, it will have at least answered a question everyone wants the answer to and Williams can then make a call on whether it is Massa or di Resta.

But if Kubica proves he can race at a high level consistently, Williams has the top-line driver it craves, mostly likely at a good price, and that will help restore its credibility.

The PR opportunity will be huge not only for Williams but for F1 as a whole. It's win-win.