The 24-year-old attacker has missed the last three games for the Rossoneri due to a hamstring injury.
Recent tests have provided some positive news and the attacker is reportedly eyeing a return against Newcastle in the Champions League next Wednesday night.
However, it has been claimed that Leao could be back in action even before AC Milan travel to England for the big game.
According to Italian daily Tuttosport (via Tutto Mercato), there is a possibility the Portuguese could be on the bench when the Rossoneri take on Atalanta in a Serie A clash.
The AC Milan medical team have cleared him to train on the grass again ahead of a potential return.
If Leao makes it through a high-intensity training session today then he could get back in training with the squad tomorrow.
A place on the bench against Atalanta is likely if everything goes according to plan or he will be in the squad to travel to England to take on Newcastle.
A win for either of the teams could get them through to the last 16 depending on the result of the game between Paris Saint-Germain and Dortmund.