Felipe Massa has reportedly agreed to come out of retirement to rejoin Williams next season, if Valtteri Bottas departs to replace the retired Nico Rosberg at Mercedes.
The 35-year-old Brazilian announced his retirement in September and brought the curtain down on his 14 years in Formula One at the end of the 2016 campaign.
But he now seems set for a U-turn.
Williams hinted last week that they could let Bottas join Mercedes in 2017 if they could tempt Massa back.
Deputy team principal Claire Williams told BBC Sport: "If we did allow Valtteri to leave, we would only do this if an experienced, credible alternative was available, such as someone like Felipe Massa, for example."
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Reports in Italy, Brazil and Britain on Tuesday evening claimed Massa has indeed been persuaded to reverse his retirement decision, with the matter now dependent on Bottas' next move.
Mercedes have had one offer for 27-year-old Bottas turned down as they search for a replacement for Rosberg.
Rosberg, 31, shocked the sport when he decided to retire just five days after being crowned champion, and it remains to be seen who will fill the German's boots to team up with Lewis Hamilton for 2017.
Earlier on Tuesday, Mercedes non-executive chairman Niki Lauda insisted his team were yet to make a decision on Rosberg's replacement and said they may wait until the end of January before making an announcement.
