Manager Stefano Pioli has confirmed the Frenchman will start the game.
Maignan has missed five months of action since suffering a calf injury back in September.
The 27-year-old missed the Qatar 2022 FIFA World Cup as a result and in his absence AC Milan's title defence has fallen flat, with leaders Napoli 21 points ahead of the defending champions.
Romanian goalkeeper Ciprian Tatarusanu has deputised creditably in Maignan's absence but Pioli is ready to throw Serie A's best shot stopper last season straight back into action for the game against Atalanta.
"Mike will play," Pioli said at Saturday's pre-match press conference.
"Tata did his duty fully. He struggled in the beginning because he hadn't played for a long time, then he found rhythm and made a good contribution. He hasn't been very well lately.
"Mike has been a lion in a cage, he's doing well and is very motivated, he will certainly give us a great contribution. He was the best goalkeeper last season and he gives us a lot.
"However, he is a player who hasn't played for five months. He will need some time, but we are expecting a lot and I am very happy with his return."
