Chelsea defender Baba Rahman could face a long spell on the sidelines after tearing the anterior cruciate ligament in his left knee during Ghana's African Nations Cup opener against Uganda.
Baba, on loan at Schalke this season, was substituted after 39 minutes and flown to Libreville for tests, which revealed the extent of the injury.
In a statement issued on Thursday, the Ghana Football Association (GFA) said Baba would return to Germany to undergo further tests and possible surgery.
"The GFA will offer all the support to the dedicated and hardworking Baba Rahman on his road to recovery," the statement said.
Baba joined Chelsea from Augsburg for £21.7 million in August 2015 but failed to establish himself as a regular starter under Jose Mourinho or Guus Hiddink.
Antonio Conte allowed the 22-year-old to join Schalke on a season-long loan at the beginning of August.