Williams' car might not be ready for the start of winter testing next week.
On Tuesday, Renault 'launched' a newly liveried and modified version of its 2018 car, with boss Cyril Abiteboul saying the 2019 machine is still "in pieces".
'Not good news'
Williams' 2019 car might also be delayed, according to Polish media sources.
Sport.pl, which is closely tracking Robert Kubica's return to Formula 1, claims the dead-last-in-2018 British team might need to cancel a scheduled filming day on Saturday.
"I do not have good news. Williams is very late with the construction of the car," said the report as quoted by an FIA-accredited engineer.
Official winter testing begins in Barcelona on Monday.