Rome: AC Milan relinquished their last, slim, hope of catching Inter at the top of the Seie A table as they subsided 2-0 on Sunday at mid-table Sassuolo.
Inter Milan can clinch a 21st title should they win or draw against Parma later this evening. Should Inter lose, only second-placed Napoli, nine points behind with three rounds of matches left, will have a chance of catching up.
Milan endured a nightmare afternoon in Reggio Emilia. It took just five minutes for Sassuolo to take the lead through Domenico Berardi.
Unrecognisable and awkward, Massimiliano Allegri's Milan side played with 10 for most of the match after English defender Fikayo Tomori was sent off in the 24th minute for a second booking.
Frenchman Armand Lauriente doubled Sassuolo's lead in the 47th minute.
A furious Allegri made a string of changes but Milan failed to get back into the game.
Following this fourth defeat in their last seven matches, the Rossoneri trail Inter by 12 points.
If third-placed AC Milan's form does not improve a Champions League spot could be in danger.
They could be caught tonight by Juventus, who face Verona later. Como are fifth, five points behind, although they too have been stuttering. Roma are sixth, another point further back.
"I understand our fans' frustration; we all want to secure Champions League qualification as soon as possible," Allegri told broadcaster DAZN.
"In these difficult times, we must keep our heads held high. We have three matches left to play, and with two wins, we'll be in the Champions League."
"There's no point dwelling on our results in the second half of the season or letting stress or anxiety get the better of us. From the next match onwards, we'll lift our heads up."
