Chelsea have confirmed that Ghana midfielder Michael Essien is out of the African Nations Cup with a knee injury.
The Premier League side are expecting the player to return to their Cobham training ground later this week where the club's own medical staff will assess the state of his injury.
Ghana's team doctor has already claimed Essien, 27, will be out of action for at least a month after suffering the injury in training.
Chelsea's Essien picked up a knee injury in training on Sunday and Black Stars press officer Randy Abbey revealed: "He will not be able to play in the tournament anymore. We still don't know the exact extent of the injury."
Scans are understood to have shown a partially torn medial collateral ligament in his left knee and damage to his meniscus.
Ghana, who started their campaign with a 3-1 defeat by Ivory Coast, must beat Burkina if they are to qualify for the quarter-finals, but striker Matthew Amoah admitted: "This is a big blow because Michael is so important to our team. We've lost the motor in our midfield, and this is very bad.''
Midfielder Anthony Annan revealed exactly what had caused Essien's injury in training.
"Michael was turning to make a pass when he just went down,'' midfielder Annan told BBC Sport. "There was no contact from any other player but those around him say they heard a click, and then the physios rushed over.''
Essien was taken to hospital in an ambulance and underwent a scan in Luanda on Sunday.
His loss will be a bitter blow to Carlo Ancelotti, although the Italian coach had to play through most of December without Essien.
The midfielder has not played for Chelsea since he sustained a hamstring injury that prevented him from joining-up with his international team-mates on time for the Nations Cup.