AC Milan head coach Sinisa Mihajlovic refuses to put a time frame on the return to action of Mario Balotelli.

The Liverpool loanee showed some encouraging glimpses of form last month and scored in the 3-2 victory over Udinese, but a persistent groin problem has kept him sidelined since the 1-0 defeat to Genoa on September 27.

Mihajlovic says Balotelli is continuing to work on strengthening the muscle but admits he cannot say when he will be available.

"The groin pain comes and goes. The doctors are trying everything to solve the problem," he said.

"He is working to strengthen the painful part, he's trying everything but he can't run. I don't know when he can come back."

Milan got back to winning ways on Sunday against Sassuolo and Mihajlovic is unwilling to abandon hope of a Champions League spot as long as his side continue to show the same desire.

"Of course I believe," he said. "If Juve believe in a Scudetto comeback, we can make a comeback to the Champions League.

"The team is more compact now. Before, we didn't attack and defend, but now it's better. But the goal is to concede fewer chances than before. 

"We must try to win. I want to see the spirit of the last few minutes against Sassuolo. They responded well straight after the goal and tried to play, and were rewarded in the end."

Gianluigi Donnarumma became the youngest goalkeeper to start a Serie A match on Sunday, at the age of 16 years and eight months, and Mihajlovic hinted that he could keep his place against Chievo on Wednesday.

"I didn't take off Lopez because he conceded a goal against Torino, but because, at the moment, Donnarumma looks better to me," he added. "We have two great goalkeepers with great personality, who are very reliable."