Chelsea midfielder Michael Essien has been taken to hospital in Angola with a knee injury, according to reports from the Africa Cup of Nations.
The Ghana captain is a major doubt for the Black Stars' must-win final group stage game against Burkina Faso on Tuesday.
Meanwhile, the Blues are anxiously awaiting news on the extent of the injury to their key midfielder.
"I don't know the extent of the injury but we will find out later," Ghana coach Milovan Rajevac told BBC Sport.
Essien started Friday's 3-1 defeat to Ivory Coast on the bench after suffering a slight recurrence of the hamstring injury which had kept him out of action for the Blues since December 8.
His participation in the tournament had been in doubt after he picked up his initial hamstring injury during a Champions League game against Apoel Nicosia last month.
However, he was cleared to report for international duty after returning to training with the Blues on January 6.