The UAE-based Gyan, who was a major doubt for the 2012 CAF Africa Cup of Nations on account of a hamstring injury he sustained last month, started the Ghana training with the rest of the squad.
However, the former Rennes player was soon forced out of the session and then had his right ankle wrapped with an ice pack.
He was then accompanied by a team official to the team's hotel, a walking distance from the training ground, for a further assessment of the injury. "We have to do more tests to know how serious this injury is," said one official.
Skipper John Mensah also did not train for the second day running because of what Ghana team doctor Percy Annan said was a muscle contusion, one that will not keep him out of the rest of the tournament.
Ghana face fellow west Africans Mali Saturday in a Nations Cup Group D match in Franceville.