Robert Kubica and Paul di Resta have both completed one-day tests for Williams in a 2014-spec Formula 1 car as part of the team’s evaluation for its 2018 line-up.
Williams is known to be considering a number of drivers to partner Lance Stroll at the team next year, including existing racer Felipe Massa.
Massa is thought to be going up against Kubica and di Resta for the 2018 drive, with the latter duo taking part in a private test at the Hungaroring in Budapest this week to aid the team’s evaluation.
After missing out on a 2018 Renault drive due to lingering questions about his physical condition six years after his rally accident, Kubica tested for Williams at Silverstone last week before getting back behind the wheel of the 2014 FW36 car in Hungary on Tuesday.
Kubica’s test was called “productive” by Williams, with the Pole handing duties over to Mercedes DTM racer di Resta on Wednesday.
Di Resta raced in F1 with Force India between 2010 and 2013 before returning to DTM, but made a surprise return at this year’s Hungarian Grand Prix with Williams when Massa was taken ill. Di Resta impressed on short notice, putting himself in contention for a full-time return to F1 in 2018.
Williams has one of the few remaining seats on offer in F1 for 2018, with Massa’s future known to be in question after a quiet campaign thus far.
The Brazilian had been due to retire from F1 at the end of last year, only for Williams to recall him after Valtteri Bottas’ late move up to Mercedes following Nico Rosberg’s surprise retirement.
Massa has made clear he would like to keep racing in F1 next year, but only if the deal is right and if Williams is determined to keep him.
While Massa, Kubica and di Resta appear to be the three leading contenders for the seat, Williams technical chief Paddy Lowe made clear in Japan there was a “large range” of drivers under consideration.
“You’ve probably seen a number of names that are floating around that we’re looking at, but honestly, the range is almost unlimited,” Lowe said.
“We will consider all ideas. We’re not in a super hurry to do so, and we’ll just make sure we land the best line-up we can.”