The hosts, who won in the previous seven meetings, had the first chance of comment when Brooke Norton-Cuffy burst past his husband and in the box, only for Mike Maignan to jump low to the right and to tip the resulting shot in safety.
Shortly thereafter, the keeper was again at the hand to make an even better stop of Junior Messiah, whose effort stabbed effort from a point-blank range went into the bottom corner.
The side of Sergio Concukicao eventually grew into a procedure, and they finally tested Nicola Leali in the 38th minute when Theo Hernandez saw a speculative 25-year strike.
Moments later, Stefano Sabelli's swinging effort was held the other end, before the Genoa goalkeeper was called up for the second time, this time it was excellent from his line to block the drive of Christian Pulisic and to ensure that the two teams went to the break.
Driving rain in the Stadio Luigi Ferraris made it increasingly difficult as the game continued, in which players from both parties struggled to keep going. However, the chances still flowed, because Hernandez had stored a free kick on a long distance.
The side of Patrick Vieira then saw Frendrup whip the wrong side of the post, before replacement Vitinha, who had only been on the field for a few seconds, scored with his first touch and a year-long drought ended by converting with a delicate volley of a thorny Aaron Martin cross.
Milan, who has raised the most number of points by losing positions in the Serie A this season, and they did properly through their own replacement, Rafael Leao, who saw a bent strike from close the balloon of the penalty spot along Leali.
Seconds later, the comeback was complete, because Frendrup accidentally smuggled a cross in his own net, shattered Genoa Hearts in the process.
Indeed, they struggled to find a real response and eventually slid into a third consecutive defeat that damages their hope to end a ten-year waiting time at a top half finish in the Serie A, while their visitors have won three away in a row for the first time since March 2024.
Flash score Man of the match: Theo Hernandez (AC Milan)
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