Mark Hughes' side is ready to submit a bid for the Gabon international, but the Premier League champion is still looking for cover after selling N'Golo Kante to Chelsea.
Stoke City is preparing a 15 million euro ($16.55 million) offer for Juventus midfielder Mario Lemina, sources tell Goal.
The 22-year-old spent last season on loan with the Serie A champion from Marseille but made just 13 appearances for the club.
Despite this, Juve exercised its option to make the deal permanent for €9.5 million, with the potential for another €1.5 million outlay in add-ons.