Crystal Palace have agreed a fee of €10m (£8.5m) plus €3 (£2.5m) in add-ons for Bayern Munich defender Chris Richards.
He has been pushed further down the pecking order at Bayern by the arrival of Matthijs de Ligt from Juventus.
Richards joined Bayern Munich on loan from FC Dallas in 2018 before the deal was made permanent in January 2019.
The defender, who can play in multiple positions, has made five first-team appearances for Bayern, 30 Bundesliga appearances at Hoffenheim and eight for the USA national team.
He would become Patrick Vieira's fourth signing of the summer after Sam Johnstone, Malcolm Ebiowei and Cheick Doucoure.