Williams technical chief Paddy Lowe has dismissed suggestions that the team's 2018 driver decision will be restricted by title sponsor Martini.

Williams currently holds the last major vacancy on the grid, with Felipe Massa's future beyond this season uncertain. The team trialled Robert Kubica and reserve driver Paul di Resta in private tests earlier this month but it is believed the team could wait until after the season-ending Abu Dhabi Grand Prix to make a decision.

But it appears there could be more than just Kubica and Di Resta to consider. A widely-held assumption within the paddock has been that the team's Martini sponsorship requires 18-year-old Lance Stroll's next partner to be over the age of 25, to avoid a situation where both drivers have to contest races without carrying any reference to the alcohol brand.

Mark Thompson/Getty Images

Mercedes boss Toto Wolff recently insisted Pascal Wehrlein, who looks set to be dropped by new Ferrari customer Sauber next year, is in the running despite being 23 years old. Wolff's former deputy Lowe, who moved to Williams from the world champions at the start of this season, has downplayed the age issue.

"What's most important for the team is to pick a driver line-up that will give us the best performance and most exciting racing potential," Lowe said. "There are some issues around advertising and Martini but if it came to it, I'm sure Martini would understand the importance -- if that's what we were to choose -- to have the best lineup for racing rather than for advertising.

"We will cross that bridge if we need to. Age is not a factor in our primary objective which is to pick the best lineup."

Marco Canoniero/LightRocket via Getty Images

If age was not a consideration, it is likely Wehrlein will have a good chance of the seat given his ties to Mercedes, Williams' engine supplier.

However, Wolff appeared to suggest during the weekend in Austin that there is a limited amount Mercedes can do to get Wehrlein the seat, saying: "At a certain stage of a driver's career there comes the moment where it's not about paying any more but standing on your own feet."

Another obvious option open to Williams if the restriction does not apply would be former GP3 champion Daniil Kvyat, also 23, who has been dropped twice by Toro Rosso since the summer break as it evaluates Pierre Gasly and Brendon Hartley for full-time drives next season. Though Toro Rosso is undecided on next year it is looking increasingly likely the Russian driver will not be retained by the Faenza outfit.