Palace have endured a mixed opening to the 2026/27 Premier League season under new boss Pierre Sage with Mateta making just one top-flight start.
The France international remains in a controversial dispute with Palace over claims the final year of his contract at the club is not valid amid a FIFA nvestgation into the matter.
Mateta joined Palace on an initial 18-month loan, before making the move permanent and signing a four-and-a-half-year deal - including an option to extend by a further 12 months - in January 2022.
Palace activated that option in 2024, meaning his present contract expires at the end of the current season.
However, this was disputed by Mateta's representatives over the summer, with United expressing an interest in the 29-year-old hitman, who has bagged double figures for goals in each of the last three Premier League seasons.
Mateta's representatives have reached out to United over a possible deal with his ongoing contract stand off meaning a move could cost around £30M.