Gabon coach Patrice Neveu has tested positive for COVID-19 and missed training on Thursday as captain Pierre-Emerick Aubameyang returned from isolation with a rallying call.
Neveu's team started their Africa Cup of Nations campaign with a 1-0 win over Comoros on Monday, but the coach appears certain to be absent for their second game on Friday when Ghana provide the opposition.
The Gabonese Football Federation confirmed Neveu's positive test result and stated training was led by assistant coach Anicet Yala, who himself tested positive on arrival in Cameroon last week.
Arsenal striker Aubameyang and Monaco midfielder Mario Lemina also returned positive results before the tournament began, but both are back on the training pitch and could be involved against Ghana.
Aubameyang said he had been able to train on an exercise bike and treadmill in his hotel room to keep up a basic level of fitness.
"Staying locked up is not easy," he said. "So we're happy to be back in training and in the squad."
Aubameyang contended it was too early to feel in any way serene about Gabon's progress in the competition and insisted he and his teammates must stay focused as Ghana await them.
"I won't say serene, but it certainly feels good to start the competition with a victory," said Aubameyang, quoted on the Gabon team website. "After that, you shouldn't think that you won the [Cup of Nations] either.
"We are going to play a very tough opponent who want to win the game, so we will have to be serious as we were in the first game and I know that we will have our chances.
"I was already very happy that the guys did the job in the first game, we are all proud of them. Now it's up to me to level up and bring everything I can to the group."
The Cup of Nations was expected to provide welcome respite for Aubameyang after strife at club level.
His Arsenal future has become clouded by uncertainty after he was stripped of the club captaincy and dropped by manager Mikel Arteta following a disciplinary breach.