Mario Balotelli "still has a lot of work to do" to get back to peak fitness, Nice coach Patrick Vieira has said.
Vieira had urged Nice to help Balotelli fulfill his desire to leave in the summer after the striker returned to preseason training late.
L'Equipe reported that Balotelli had weighed 100 kilograms, 12kg above his optimal weight, when he returned.
The 28-year-old missed Nice's first three matches of the season through suspension but played 75 minutes against Lyon before the international break.
"In the game against Lyon, you saw that he's not yet ready to play 90 minutes. He still has a lot of work to do," Vieira said.
"We'll have to be patient with him, because unfortunately he didn't do the start of preseason training.
"Regarding his attitude, he's good, he's working well. He's got a positive attitude. That's the most important thing."
Balotelli was criticised for his performance in Italy's recent 1-1 draw with Poland.
Coach Roberto Mancini said he had had a "bad game" and he was sidelined for Monday's Nations League defeat to Portugal.