The Red Devils agreed a deal for the 18-year-old over the summer, and he is due to arrive at Old Trafford in the coming days, having finally received a work permit.
Atalanta coach Gian Piero Gasperini said on Saturday that the Italian club were keen to keep Diallo on loan until June, telling reporters: "There is an internal solution that could be very interesting, which is Amad Diallo. Clearly, Manchester United own him, but he could remain with us for a few more months.
"I really like him, he's only 18, and I'd like him to stay until June, but obviously it depends on his club."
However, according to the Manchester Evening News, the 20-time English champions 'have no plans' to allow the right-sided attacker to remain with Atalanta until the summer.
The report claims that United boss Ole Gunnar Solskjaer is keen to introduce the teenager into the first-team squad 'as soon as possible', suggesting that he could be involved in the second half of the season.
Diallo, who was born in the Ivory Coast before moving to Italy at a young age, has made two substitute appearances for Gasperini's side during the 2020-21 campaign.
The youngster will allegedly cost United an initial €25m (£22.7m), but the deal could eventually rise to €40m (£35.5m). body check tags ::