West Brom have made an offer of about £13m for Morgan Schneiderlin, who will be allowed to leave Manchester United for "the right offer".
Baggies boss Tony Pulis confirmed the bid, while United manager Jose Mourinho said: "If the offer is right and our board thinks so, I would not stop him."
The midfielder, 27, joined the Red Devils from Southampton for £25m in July 2015 but has played only 11 minutes of league football this season.
Everton are also interested.
Mourinho said Schneiderlin had asked to leave, adding: "If he is playing regularly, I have a right to say 'no way'.