Crystal Palace have announced that Kwesi Appiah is thought to have suffered an anterior cruciate ligament injury while on international duty with Ghana.
The striker, who spent last season on loan with Cambridge United and Reading, was included in the squad for internationals against Togo and Mauritius, but sustained the injury in training.
A statement from the club said: "Crystal Palace striker Kwesi Appiah looks to have suffered a serious injury whilst away on international duty this week.
"The 24-year-old underwent tests on a suspected anterior cruciate ligament injury, which he sustained during Ghana training, ruling him out of their AFCON 2017 Qualifier against Mauritius on Sunday 14th June. The Black Stars also face Togo in a friendly tonight, though Appiah will obviously play no part."
The striker scored nine goals in 29 club appearances last season, while also scoring once in four matches for Ghana at the Africa Cup of Nations.