The internationals get under way for the Reds involved on Thursday evening, with Altay Bayindir (Turkey) and James Scanlon (Gibraltar) potentially involved against Georgia and Albania respectively.
Matthijs de Ligt is with the Netherlands squad as they face Poland later on, while Cameroon, featuring Andre Onana and Mbeumo, tackle Eswatini.
United's next assignment is the Manchester derby, against City, in the Premier League on Sunday 14 September.