With Lance Stroll to make his debut with Racing Point Force India tomorrow afternoon, thereby effectively rubber-stamping the youngster's move to his father's team, the only remaining vacant seat on the 2019 grid is that alongside Daniil Kvyat at Toro Rosso.
Given the mission of "beating Pierre Gasly" in order to retain his seat, it is looking unlikely that Brendon Hartley will be retained, though many would argue that the kiwi has not been given a fair crack of the whip.
In recent times Alexander Albon has been linked with the seat, the Thai driver finishing third in the 2018 F2 championship, behind George Russell and Lando Norris who both move up to F1 next season. However, there are known to be issues with Nissan e.dams which Albon under contract for the forthcoming Formula E season.
Meanwhile, for reasons best known to itself, Toro Rosso has revealed that Sean Gelael will drive the STR13 tomorrow, before handing over to Kvyat on Wednesday.
Though the test is mainly for Pirelli's benefit, allowing the Italian manufacturer to run its 2019 compounds, a number of teams are taking the opportunity to run their new drivers therefore one has to wonder if Albon is to partner why he isn't in the car.
Gelael, who drove the STR13 in the post-Spanish and Hungarian GP tests, finished 15th in this year's F2 championship, but the youngster does have substantial backing in the form of his father who holds the Kentucky Fried Chicken franchise for Indonesia.
Check out our Sunday gallery from Yas Marina, here.