Kubica made a fairy tale return to F1 after he was given a seat by Williams for this season, eight years after a near-fatal rally car accident. However, Kubica has struggled for form and has only beaten his teammate once this season, at the French Grand Prix, whereas George Russell has impressed with the limited resources.
PKN Orlen, a Polish oil company and one of Kubica's sponsors has tried to put to bed speculation he could be set to be replaced at Williams midway through the season, with reports suggesting Esteban Ocon and Nicolas Latifi waiting in the wings.
A spokesperson for Orlen said on sport.pl: "Speculation regarding the limitation of Orlen's support for Williams is untrue.
"The contract with the team is for the whole season and is closely related to the participation in the races of Robert Kubica.
"The rules of financing and the team's obligations are precisely defined in the contract."