“It’s not looking so good but Gyan is a very strong boy,” said Grant when asked about the extent of the problem.
“We will need to wait and see. We will have a scan and then we will know better.”
Gyan was making his 99th international appearance and was looking to score his 50th goal for his country, but he went down with a groin injury towards the end of the first half and eventually came off.
Jordan Ayew replaced him as Ghana lost the Group D game in Port-Gentil 1-0.
Gyan described himself as a “victim” of a dreadful playing surface that has already come in for widespread criticism.
He added: “I felt a stretch in my adductor, so I don’t know the extent of the injury.
“I’m in pain right now. Tomorrow (Thursday) I will see the doctor. We will go for the MRI and then we can decide the extent of the injury.”
The Black Stars, runners-up in 2015, will face DR Congo in the quarter-finals in Oyem on Sunday.
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