Elneny picked up a calf problem while away with the Egypt national team.
The midfielder’s injury was confirmed by Egypt bosses – but they would not give any further information.
Mohamd Elneny has suffered an injury playing for Egypt
Elneny has started just six league games for Arsenal all season
Egypt are set to face Morocco in the AFCON quarter-finals tonight.
If they crash out of the competition then Elneny will head straight back to the Gunners.
If Egypt win tonight then Elneny will miss Arsenal’s crunch clash with Chelsea on February 4 regardless of whether he is fit or not.
Premier League players returning early from the Africa Cup of Nations
Thu, January 26, 2017
Click through the gallery to reveal which Premier League African stars are returning home after being knocked out of the AFCON group stages
1 of 11
Click through the gallery to reveal which Premier League African stars are retur
Arsenal sit second in the Premier League but eight points off leaders Chelsea.
The Blues could stretch that gap to 11 if they beat Liverpool on Tuesday and Arsenal lose to Watford.
Elneny, 24, has made 22 appearances for club and country this season, although he has started just six league games.