The Croatia international is believed to have been discussed during talks over a potential Romelu Lukaku-Paulo Dybala swap deal.
However, his move will be a separate affair that will cost the Red Devils €10-15 million, Tuttosport reports.
The two clubs are in advanced talks for the 33-year-old and the deal could be confirmed on Monday.
United enquired about the availability of Mandzukic at Easter time this year, but the striker turned them down having signed a contract extension in April.
However, he isn’t considered a part of new coach Maurizio Sarri’s plans and is therefore expected to agree to the switch this time round.
Mandzukic started 23 Serie A matches in 2018/19, scoring nine goals and laying on another six assists.
Get the best features, fun and footballing frolics straight to your inbox every week.
Thank you for signing up to Four Four Two. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.