Williams is in "no rush" to take a decision on who will fill its second Formula 1 seat for the 2019 season, but has drawn up a "short shortlist" of candidates to partner George Russell next year, according to deputy team boss Claire Williams.

Williams announced earlier this month it had signed Mercedes junior and current Formula 2 championship leader Russell for 2019, acting as a break with its recent approach of signing two drivers with sizeable financial backing.

Russell is expected to take the seat of Lance Stroll, who is due to move up to Force India for 2019 following his father's takeover of the team over the summer, while Williams' other driver, Sergey Sirotkin, is working on retaining his seat for a second year.

Other candidates for the seat include Formula 2 racer Artem Markelov, current team reserve Robert Kubica and Force India's Esteban Ocon, but Williams is happy to take her time before making a final decision.

"I’m not in any rush to do that. We have a short shortlist which we are working through at the moment, and as much as it was important securing a driver with talent for the first seat, it will be for the second seat as well," Williams told Crash.net in Austin.

"We have options. We just need to make sure that we secure the best driver that we possibly can based on the criteria that we set ourselves for that seat."

Asked about a possible shortfall in income by opting against signing two drivers bringing financial backing to the team in 2019, Williams stressed the team had already made this up, allowing it to take the decision to sign Russell and also consider a driver such as Ocon, who would also not arrive with any financial aid.

"We’ve already made up that shortfall, and that was why we were able to secure George," Williams said.

"That’s not the second driver’s responsibility to secure any finance that enabled us to have George in the first seat."