Goalkeeper Edouard Mendy has returned to Chelsea after injuring his right thigh while training with Senegal.
Chelsea said Mendy “had a medical examination in a hospital in Rabat, where Senegal are due to play Morocco”.
The club added: “Mendy has since returned to Chelsea where he will undergo further examinations.”
The player’s agent told the BBC the injury is “not that bad” and his recovery should take about 10 days.
Chelsea return to action in the Premier League with a home game against Southampton on Saturday, 17 October (15:00 BST kick-off).
Senegal play Morocco in a friendly on Friday (19:00).