Kubica tested with Renault in August as he seeks a way back into Formula 1

Robert Kubica set the fastest time by a Williams driver at this week's Abu Dhabi test, as the team try to establish whether to sign him for 2018.

Kubica is aiming to return to Formula 1 seven years after suffering life-changing injuries in a rally accident.

The 32-year-old Pole set a best time 0.5 seconds quicker than Renault reserve driver Sergey Sirotkin, who is also being assessed by Williams.

Kubica was 0.1secs faster than race driver Lance Stroll on Tuesday.

Former BMW Sauber and Renault driver Kubica, who has only partial movement in his right arm, set his fastest time during the final two hours of running on Wednesday, after Sirotkin took the wheel for the morning and half the afternoon session.

Kubica completed 100 laps - nearly two race distances - during half a day's running on Tuesday, his first in the 2017 Williams car, before handing over to Stroll for the afternoon.

On Wednesday, his deficit to Ferrari's Sebastian Vettel, who set the fastest time of the day at the end-of-season test aimed at trying out Pirelli's 2018 range of tyres, was within 0.1secs of that of the fastest Williams driver Felipe Massa in qualifying at the Abu Dhabi Grand Prix last weekend.

Kubica, like Vettel, was using the fastest 'hyper-soft' tyre when he set his time, while Sirotkin set his best time on the 'soft', which is three grades harder.

What happens next?

Williams will now analyse the data from the test at their factory in the UK, seeking to eliminate all the variables to get a clear idea of Kubica's pace, and hope to make a decision on a partner for Stroll in 2018 by mid-December.

Following Massa's retirement, Kubica is in contention for the drive with former Red Bull and Toro Rosso driver Daniil Kvyat, Sauber driver Pascal Wehrlein, Williams reserve Paul di Resta and Sirotkin.

Kubica is the favourite for the seat and was expected to get it as long as Williams did not see any concerning signs at the test.

Robert Kubica in Formula 1 One race win: 2008 Canadian Grand Prix

One pole position: 2008 Bahrain GP

Four full seasons as F1 driver

Teams raced for: BMW Sauber and Renault

Last race: 2010 Abu Dhabi GP

Kubica did not speak to the media after his second day's running at Abu Dhabi but said on Tuesday: "I have some limitations and I have to adapt, but one positive thing is how my body is reacting and how natural I feel every day when I am driving these cars, so that gives me a lot of confidence.

"There are a lot of people wishing to see me back because of the story, but there is no discount for the story.

"I have to make sure if I get the chance I am ready and be as best prepared as I can.

"I appreciate it because there is a lot of hope and wish of a lot of people, but in the end I know the reality. The reality is once I am in the car there is no story any more and the job has to be done.

"First I have to be sure I am able to do it and a day like today is giving me quite a lot of confidence that things can work out pretty well.

"For my standard, it has to be high level. If I do come back I am not here to make up the numbers. Although I am seven years away with my limitation, I have to make sure I can provide the best of Robert Kubica.

"I am very demanding of myself. I understand my situation so I try to adapt.

"The worst thing I would like to do is convince myself I can do it and then have troubles.

"There are question marks have to be answered for the team but also for myself.

"In general I see big improvements day by day so I can expect things getting better and that's why I say I would be disappointed if nothing else happens because I am putting in a lot of effort and there is a good chance I am able to do it."

Kubica won the Canadian Grand Prix in 2008

A fairytale return?

Should Kubica be recruited, it would complete what is already a remarkable story, after he fought back from close to death following the accident that curtailed his career on the eve of the 2011 F1 season.

As well as a partially severed right arm, Kubica suffered multiple fractures throughout the right-hand-side of his body after his rally car was pierced by a metal roadside barrier.

It took Kubica until last winter to get himself back into a physical condition in which he thought it might be possible to drive an F1 car again.

Kubica did three tests for Renault this summer before the team decided not to pursue signing him, saying they had "unanswered questions" about whether he could return.

But Williams were attracted by the idea of signing a man who was renowned for pace, consistency and technical feedback before his accident.

He won the 2008 Canadian Grand Prix for BMW Sauber and was regarded as one of the leading talents in the sport at the time.

Kubica impressed Williams in two tests alongside reserve driver Di Resta at Silverstone and the Hungaroring in October.