A disappointing point from the Milan derby allowed Lazio to leapfrog Massimiliano Allegri's side into third with victory over Pescara on Monday night, while Balotelli broke down in training just days after being handed a 10,000 euro fine for gesturing at the Inter Milan fans.
Inter were simultaneously fined 50,000 euros as a section of supporters were seen directing racist abuse at the Italy striker, who has an infinitesimal chance of facing Lazio at San Siro.
Head coach Allegri told acmilan.com: "I am 99.9 per cent sure that Balotelli will not feature because he has suffered bad bruising to his tibia with a haematoma that has stopped him training properly all week long."
Balotelli's international team-mate Stephan El Shaarawy committed his future to the Rossoneri until 2018 this week but his participation is also in doubt.
Allegri added: "I will assess El Shaarawy today and if he doesn't play then I will use Robinho because he's in good shape. (Giampaolo) Pazzini is also fit and they are both ready to play in this important game."
Defeat to Lazio would see Milan beaten at home for the first time since November 11, allowing the capital club to pull five points clear in third place while leaving Allegri's side vulnerable to the chasing pack.
"When you play against the big teams there's always an element of risk," he added. "Tomorrow [Saturday] will be a different game, a difficult one, Lazio have a lot of personality and a really good defence.
"I don't think it will be a spectacular match but I hope I'm wrong. We will do everything we possibly can to win because with our league position and the number of days left until the end of the season, we need two good results from every three.
"There are certain matches in the season which you have to win. We will see where we are after this game against Lazio."
Defender Philippe Mexes serves a one-match ban with Daniele Bonera, Nigel De Jong and Mathieu Flamini facing late fitness tests as the Rossoneri target a first win over Lazio since November 2009.
That poor run pales in significance to the hoodoo that surrounds the Romans' joyless trips to San Siro, where they have not beaten Milan since 1989.
Breaking taboos, however, comes a distant second for Lazio head coach Vladimir Petkovic.
He told La Repubblica: "I just want the real Lazio to turn up in Milan, arriving with our heads held high and looking to both dominate and win a match which is certainly important, if not decisive.
"How will we do it? There is no secret recipe. We have to believe in what we are doing because if we can do that then we will be able to match any side."
Petkovic is missing Abdoulay Konko, Marius Stankevicius, Miroslav Klose, Cristian Brocchi and Stefano Mauri through injury.