The two have played just 220 Premier League minutes between them across Man United’s opening nine games.
Mainoo, 20, requested to leave the club on loan in the back end of the summer transfer window, but the club quickly turned his request down.
As for Zirkzee, 24, he has grown frustrated with his lack of minutes and was hoping to secure a move away in January, with West Ham linked.
Now, according to The Sun, United will turn down any advances for the two wantaway stars in January regardless of any requests or advances.
It’s understood that with the club set to lose the likes of Bryan Mbeumo, Amad Diallo, and Noussair Mazraoui to AFCON, they are keen on retaining all their players.
The tournament is set to start just before Christmas and will conclude on January 18th, meaning United could be without at these player for at least six domestic fixtures.