The Rossoneri lost further ground on the top three Serie A teams after being held to a 1-1 home draw by Lazio on Wednesday night.
With just two wins collected in the their past eight games, the pressure is mounting on Allegri.
Milan sit 10th in the table, 13 points behind Juventus, who are third and hold the last Champions League qualifying spot.
"The only way to come out of this tough situation is by working hard," Allegri told the club's official website, www.acmilan.com.
"It's normal that by taking the results we are getting, we are far away from the third position.
"If the top three teams (Roma, Napoli and Juventus) maintain this high rhythm then it will be impossible for us to catch them.
"We need to bounce back and try to climb up in the standings, starting with a win against Fiorentina. We need to give our best to obtain maximum points."
The Rossoneri face a stern test against a Fiorentina side that saw their unbeaten run at home come to an end in Wednesday's 2-1 defeat to Napoli.
The outcome dropped the Viola to sixth place.
Napoli and Juventus go into their games against Catania and at Parma, respectively, in hot pursuit of Serie A leaders Roma having each won their past two games.
Juventus rolled over Catania 4-0 on Wednesday to go level on 25 points with Napoli.
Both teams lie two points adrift of Roma, who square off against Chievo on Thursday before facing Torino this weekend.
Cagliari face a stern test on Sunday with Hellas Verona boasting a perfect record at the Marc' Antonio Bentegodi stadium.
Verona beat Sampdoria 2-0 in midweek to climb to fifth place, level on 19 points with Inter Milan.
Inter take on Udinese at the Friuli stadium with a sense of urgency, with Walter Mazzarri's men having collected just one victory in their past five games.
Lazio will fancy their chances of taking at least a point against Genoa with the Biancoceleste unbeaten at home this season.
The Romans have failed to win a game on the road but have taken 13 of their current 15 points at the Stadio Olimpico.
Bologna welcome bottom-side Chievo to town inspired by their recent resurgence.
The Rossoblu followed their 1-0 triumph over Livorno with a convincing 3-0 victory at Cagliari on Wednesday to remain above the relegation zone.
Sampdoria have won just once at home this season and take on promoted-side Sassuolo on Sunday.
Atalanta will look to build on their 1-1 midweek draw against Inter with a win at Livorno.
The Bergamaschi have won just one while they have lost four of their games on the road this season.