The move comes after the Red Devils were deterred by Aston Villa's asking price for Ollie Watkins, who is valued at £60m.
While Watkins is somewhat established, United is willing to take a chance on Sesko's potential, considering he is younger and relatively unproven.
RB Leipzig is expected to negotiate a similar fee for Sesko, who is 22 years old, as Villa's asking price for Watkins.
Newcastle United is also monitoring Sesko as a potential replacement for injured striker Alexander Isak.
