Williams has denied it has concluded a deal with Robert Kubica to run the Pole alongside Lance Stroll next season.
Kubica tested for the Grove-based outfit twice recently, running at Silverstone and Hungary with a 2014-spec car along with Paul di Resta, the second candidate for a 2018 Williams drive.
The 32-year-old is scheduled to drive a new-spec car at the Abu Dhabi post-race Pirelli tyre test next week, but Williams is denying a deal is done and dusted.
"Although conversations are ongoing with Kubica, it is still yet to be finally decided who will replace Massa," said a Williams statement.
"We will make an announcement when we have something to announce but nothing is planned this weekend in Abu Dhabi."
Kubica in being helped with his sensational F1 comeback efforts by 2016 world champion Nico Rosberg and his management team.
It is rumored that the group has put together a multi-million dollar sponsorship package to help the Pole secure his drive.
Kubica last raced in Formula 1 in 2010, his career grinding to a brutal halt following a rally crash in 2011 which left the driver with a seriously impaired right arm.
The winner of the 2008 Canadian Grand Prix ramped up his comeback efforts last spring, first testing a GP3 car before running with Renault in a 2012 Lotus E20.
In addition to Kubica and di Resta, the frontrunners for the Williams seat, the team is also considering Mercedes protégé Pascal Wehrelein and former Toro Rosso driver Dany Kvyat.
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