Ghana captain Asamoah Gyan was diagnosed with malaria while at the African Nations Cup and was admitted to the hospital in the remote eastern town of Mongomo in Equatorial Guinea, the Ghana Football Association (GFA) said on Sunday.
The GFA confirmed that Gyan was taken to the hospital on Saturday night, but released on Sunday morning after "a mild bout" of malaria.
"The illness was detected at an early stage and Gyan is responding well to treatment," the GFA said in a statement on its official website.
Ghana's squad is based in far-eastern Equatorial Guinea for the group stage of the tournament. Mongomo -- on Equatorial Guinea's eastern border with Gabon -- is one of two remote and little-known venues chosen to host games after Equatorial Guinea stepped in at short notice to take over the tournament from initial host Morocco.
Gyan is now doubtful for Ghana's first game of the tournament against Senegal on Monday, the GFA said, and he will be monitored by doctors after being released from the hospital. The striker had been unable to train for two days.
Senegal's Sadio Mane is also a doubt for the match with a calf problem. Mane, 22, was included in Senegal's 23-man squad for the tournament despite suffering a calf injury in Southampton's Premier League win over Arsenal on New Year's Day, a problem which his club said would require him to be on the sidelines for several weeks.
Alain Giresse leads Senegal into their first Group C encounter in Mongomo uncertain whether Mane can start, but the Frenchman, 62, believes the exciting forward will play some part in the group stage campaign.
"If Mane is with us, it's because he is ready," Giresse, who was forced to leave West Ham United's Diafra Sakho out of his squad for the finals due to a back injury, told media.
"We still don't know when he will play though. Everything will depend on his recovery. For the moment, we still haven't taken a decision on the matter. Perhaps he'll play the first game, perhaps not."
ESPN FC correspondent Ian Holyman contributed to this report.