Sassuolo had scored at least twice in each of their previous six home matches, but that looked unlikely to continue here.
A looping Vasilije Adzic header and long-range strikes from Darryl Bakola and Armand Lauriente all sailing over the bar was the extent of their efforts in the first quarter of the match, though that was more than a couple of harmless blocked efforts for Milan.
The visitors finally created an effort of note in the 33rd minute when a free-kick from out wide was headed narrowly over by Adrien Rabiot, as Arijanet Muric came to claim but got nowhere near it.
Two minutes before the break, one of the goalkeepers was finally forced into action, as Goncalo Ramos took on a shot from a tight angle which Muric batted away, before the Rossoneri recycled the ball well, and when Ramos met a delivery with his head, the Bosnian reacted well to turn it over his crossbar.
Suddenly, Muric was being overworked, as he got down low to deny Diego Moreira and was at full stretch to reach a Strahinja Pavlovic header in added time.
With four of Sassuolo’s five previous matches this season seeing more goals after the break than before it, and Milan entering the round with the best record after half-time in the division, a more entertaining second half looked to be in store.
In truth, it was another slow burner, as neither team had an attempt until the 59th minute, when Mike Maignan smothered a close-range Adzic effort, before Ramos was wasteful from the edge of the area seconds later at the other end.
Milan had scored five times this season between minutes 61 and 75 of away matches, and they made it six in the 63rd of this contest, when Luka Modric threaded a ball through for Rabiot to rifle past Muric at his near post despite a tight angle.
However, the lead lasted all of five minutes, as Lauriente delivered a low corner which ricocheted around the away side’s box before falling to Cas Odenthal, who slotted his second of the season through a crowded six-yard box.
Muric was busy again late in the half, denying Alphadjo Cisse’s curling shot with six minutes left, then at the other end, the Neroverdi had the ball in the net again but Kristian Thorstvedt’s finish was quickly ruled out for a foul.
Honours even means Alberto Aquilani’s side have dropped points at home for the first time this season, while Il Diavolo have gone unbeaten over the first six matches of a Serie A season for the first time since 2022.
Flashscore Man of the Match: Arijanet Muric (Sassuolo)