Manchester United fear Benjamin Sesko could be out for up to a month after limping off through injury against Tottenham Hotspur.
Ruben Amorim's side finished that 2-2 epic before the international break with 10 men after Sesko was forced off with a knee issue with United having made all their substitutions.
Sesko, who pulled out of international duty with Slovenia to begin his injury rehab at Carrington, has avoided serious damage but is still set for an extended spell on the sidelines.
Daily Mail Sport understands that while United have not put a fixed timescale on the £73.