Nice coach Lucien Favre said he substituted Mario Balotelli at half-time of Nice's UEFA Europa League defeat to Krasnodar because the summer signing had a sore throat.
Balotelli, 26, was replaced by Alassane Plea at the break in Russia as Nice slumped to a 5-2 defeat in their second Group I game.
"Mario has a cough," Favre told media postmatch. "Things went downhill very quickly. He'd actually asked to come off after 25 minutes.
"Then after a difficult spell, he told us it was a little better. We tried to keep him 5-10 minutes more, but he had a sore throat, it wasn't possible.
"The doctors will explain the symptoms better than me. But we mustn't hide behind him going off as an excuse, because we were struggling with him on the pitch."
Balotelli, who joined Nice from Liverpool on deadline day, has scored four goals in two league appearances for the Cote d'Azur outfit. His European outing was only his fourth game for Nice since completing his move.
The Italy international is now a doubt for Nice's league game against Lorient on Sunday.