Robert Kubica's sensational Formula 1 return looks increasingly unlikely to happen, at least in 2018, with Williams now leaning toward Sergey Sirotkin.
It's believed Kubica is no longer in the running, meaning Williams are set to choose between Sirotkin, Paul di Resta and back-up Daniil Kvyat, though the former is very much the favourite option given the substantial financial backing the Russian brings.
Although Kubica had been the preferred option prior to his recent Abu Dhabi outing for the team, sources suggest the Polish driver doesn't meet the performance levels Williams expected, with Sirotkin outpacing him during the test.
It's believed Kubica's outright performance was also the reason Renault chose to chase Carlos Sainz as a late-season replacement for Jolyon Palmer, despite Kubica's multiple tests with the French manufacturer.
22-year-old Sirotkin, who most recently held a Renault reserve role, brings backing worth an estimated $20 million (£15m) from SMP Racing.
Kubica could now head back to the World Endurance Championship where he secured a seat before pulling out ahead of the season opener in order to chase his dream F1 return.
