Crystal Palace boss Patrick Vieira wants to switch to a back three next season.
The decision will mean Palace needing to find a new centre-half signing.
Palace relied heavily on Marc Guehi and Joachim Andersen last season in a back four. They have already let go of veteran Martin Kelly.
And versatile Cheikhou Kouyate is out of contract, though talks over a new deal are underway.
Vieira's plans could open the door for USA defender Chris Richards, 22, at Bayern Munich, says The Sun. The Eagles are also weighing up a loan move for former right-back Aaron Wan-Bissaka, 24, who is available from Manchester United.
Wan-Bissaka is capable of playing on the edge of a back three.
