Gennaro Gattuso's Milan are in dire straights at the moment and a loss on Sunday could see them enter crisis mode.
Draws against Cagliari, Atalanta and Empoli have seen I Rossoneri slip down into Serie A's bottom half, and their performances in each don't suggest they'll be moving up anytime soon.
Sassuolo, on the other hand, hope to push on from the 11th place finish of last campaign. Currently sitting in third with their only loss so far at the hands of Juventus, Roberto De Zerbi's team are flying high.
Here's how Milan could look for Sunday's encounter.
1. Goalkeeper & Defenders
Davide Calabria (RB) - A product of Milan's youth system, the young Calabria could soon make his Azzurri debut.
Mateo Musacchio (CB) - With Mattia Caldara out for the long term, Argentine Musacchio will start at centre back once again.
Alessio Romagnoli (CB) - I Rossoneri's captain made a terrible mistake against Empoli, which resulted in his side throwing away a much needed win. He will be hopeful of an improvement in this must win match.
Diego Laxalt (LB) - Favoured to Ricardo Rodriguez recently, it's probable Gattuso chooses the Uruguayan to fill a role at full back.
Franck Kessie (CM) - The Ivorian missed two glorious chances in Thursday's draw and will want to bounce back this time around. His physicality against both Alfred Duncan and Manuel Locatelli will be integral to victory.
Lucas Biglia (CM) - Scoring AC's only goal versus Empoli, the combative midfielder will hope to lead by example against Sassuolo.
Giacomo Bonaventura (CM) - The creative linchpin of I Rossoneri's side, Bonaventura's man of the match performance against Roma gained Milan their only Serie A win so far. He will need to create some goalscoring opportunities if his team are to succeed on Sunday.
Suso (RW) - A disappointment while at Liverpool, the Spaniard has somewhat reinvented himself in Italy. Milan's standout against Empoli, onus may be on him to grab a result here.
Fabio Borini (ST) - With Gonzalo Higuain out injured, Gattuso has a choice to make. Due to the fact Patrick Cutrone is not yet 100% fit, it's likely that former Sunderland man Borini will lead the line.
Hakan Calhanoglu (LW) - Brought in from Bayer Leverkusen, the Turk didn't exactly set Serie A on fire in his debut season. It AC are to qualify for this Champions League this campaign, he will need to give more.