The proposed swap deal that will see Alexis Sanchez and Henrikh Mkhitaryan exchange clubs is reportedly being held up by paperwork.
Arsenal and Manchester United are understood to have agreed personal terms with their respective targets and medicals have been passed.
Before official confirmation can be given, however, both Sanchez and Mkhitaryan are awaiting new work permits to be finalised.
According to Sky Sports News, their existing permits must be brought in line with the lengths of their deals, as per Home Office regulations.
Sanchez is said to have been spotted at the immigration office in Liverpool on Monday, shortly before being joined by Arsenal-bound Mkhitaryan.
No further snags are expected, though, and a joint-announcement by both sides is still expected to be made before the end of Tuesday.