Leonardo Bonucci's reckless first-half sending off forced AC Milan to battle for a 0-0 draw at home to struggling Genoa on Sunday.

The Rossoneri were left with 10 men for over an hour following Bonucci's elbow on Aleandro Rosi and the disadvantage proved too great an obstacle in their bid for a first Serie A victory in four matches.

Instead, under-fire manager Vincenzo Montella will come under greater pressure for failing to guide his side past a team that has now won only one of nine in the league.

Milan had carried the weight of three successive domestic defeats into the contest and their task was only made more difficult by Bonucci's moment of madness, with the Video Assistant Referee (VAR) involved in dismissing the captain.

And an air of frustration at San Siro almost turned to anger when Andrea Bertolacci, on loan at Genoa from Milan, curled agonisingly wide of the post.

The home survived that scare but lacked the resources to create a clear-cut chance for a winner, leaving Montella seemingly on the brink of the sack.

Milan started on a positive note with Hakan Calhanoglu, who missed the derby defeat to Inter through suspension, heading wide from Giacomo Bonaventura's cross.

Fabio Borini then gave Mattia Perin his first work in the sixth minute, the goalkeeper forced to push a clever low effort around his near post.

That early momentum waned, however, and Milan's frustration boiled over in the 25th minute when Bonucci was given his marching orders.

The Italy defender was looking to attack a free-kick when he bloodied Genoa wing-back Rosi with a stray elbow to the face. After consulting with the VAR, the referee deemed the incident worthy of a straight red card.

Montella immediately strengthened his defence by withdrawing Calhanoglu for Alessio Romagnoli and, after Gianluigi Donnarumma held a firm Luca Rigoni header, the 10 men responded well to keep scores level at the break.

Sent out on loan by Milan, Bertolacci came within inches of burying the knife into his parent club as his curling effort from the edge of the area drifted around the right post.

Both goalkeepers were being tested more regularly by the hour mark as Perin claimed a dangerous free-kick at one end, while a diving Donnarumma watched Miguel Veloso's shot whistle wide.

Franck Kessie single-handedly brought about the hosts' best chance of the second half by carrying the ball from defence to attack, but the dynamic midfielder passed up options inside and instead drove his finish the wrong side of the near post.

Big-money signing Nikola Kalinic should also have done better when Suso spotted him unmarked in the penalty area, only for the Croatian striker's touch to evade him at the critical moment.

Genoa did have one final opportunity to turn their numerical advantage into a second straight league victory but, after striding clean through on goal, substitute Gianluca Lapadula lost his feet and was hauled in by Cristian Zapata.

Next up for Milan is a visit to in-form Chievo on Wednesday before they return home to face champions Juventus next weekend.