Benjamin Seskos Manchester United career is yet to truly take off following his big-money move in the summer and its not been helped by a knee injury sustained late on in the 2-2 draw at Tottenham on 8 November.
The 22-year-old striker signed from RB Leipzig in August but has taken a while to get up to speed after missing most of pre-season and adapting to a new league.
Sesko's absence set to overlap with AFCON departures
Sesko sat out Slovenias final two World Cup qualifying games, and the extent of his injury was announced over the international break.
Sesko is expected to miss about a month, though the precise length of his absence is still to be determined.
Amorim is set to provide an update this Friday at a press conference ahead of Uniteds home clash with Everton on Monday night.
His absence could overlap with the departure of fellow forwards Amad and Bryan Mbeumo for the Africa Cup of Nations, which kicks off in Morocco on 21 December, which is already a major concern for United.
With just one game a week this season and reported improvements across the board fitness-wise under Amorim, United have had far fewer injuries than in recent seasons with the returning Lisandro Martinez their only other current injury absentee.
With Sesko out, the main decision for Amorim ahead of the visit of former United manager David Moyes to Old Trafford on Monday will be who starts up top.
Manchester United take on Everton on Monday night when Premier League action resumes.
