Williams is considering allowing Valtteri Bottas to leave the Formula 1 team for Mercedes in 2017, with Felipe Massa a potential replacement.
Mercedes contacted Williams to discuss the possibility of releasing Bottas as it needs a team-mate for Lewis Hamilton following Nico Rosberg’s shock retirement.
Williams rejected the offer, which included a reduction in the cost of its 2017 engine supply as well as the opportunity to run Mercedes reserve Pascal Wehrlein.
However, it is believed a second proposal is being formulated.
Williams is keen to hold on to Bottas because of his experience, given his 18-year-old team-mate Lance Stroll will be making his F1 debut.