Michael Essien has been taken to hospital for tests on a knee injury sustained during the CAF Africa Cup of Nations, according to reports in Angola.

The Chelsea midfielder, whose build-up to the tournament was hampered by a hamstring problem that also prevented him from starting in the 3-1 defeat to Côte d’Ivoire on Friday, is now a serious doubt for the Black Stars' must-win match against Burkina Faso on Tuesday.

"I don't know the extent of the injury, but we will find out later," Ghana coach Milovan Rajevac said.

Essien, 27, trained this morning, but failed to complete the session before being taken to a local hospital in an ambulance.

Rajevac will be desperate for his key man to recover in time for Tuesday, as anything less than a win will cause one of the powerhouses of African football to make an early exit.