It was an open match in the early stages with both teams desperate to win, and Federico Dimarco had the ball in the back of Mike Maignan’s net inside seven minutes but had the goal ruled out due to Lautaro Martinez roaming offside before squaring to him.
Christian Pulisic’s shot was deflected behind and Nicolo Barella had a shot saved before a period in which positive and patient play was met by defensive resilience for both sides.
The Nerazzurri got on top as the half-hour mark approached, but Martinez suffered frustration in front of goal.
The captain turned Hakan Calhanoglu’s cross wide from an awkward position, then had a goal ruled out due to Barella roaming offside, was denied a corner after Strahinja Pavlovic deflected his effort wide and finally blazed a shot off-target.
The Rossoneri soon provided a threat of their own, with Tijjani Reijnders’ strike requiring an eye-catching save, before Benjamin Pavard made a superb tackle to stop Rafael Leao reaching the Dutchman’s through ball.
They weren’t to be denied before half-time, though, as Yann Sommer got a hand to Leao’s low ball but could only direct it towards Reijnders for the midfielder to open the scoring.
Loose play offered Inter a big chance under a minute after the restart but Martinez fired straight at Maignan, and a break shortly after culminated in Denzel Dumfries blocking Leão’s shot as the second period got off to a blistering start.
Fikayo Tomori then matched Stefan de Vrij’s jump to deflect his header behind, before a shot from Dimarco was denied.
Simone Inzaghi made his move with a triple substitution in the 63rd minute, but a frustratingly familiar story followed for Inter as Martinez had another goal ruled out.
Yann Bisseck then saw his header hit the post and Henrikh Mkhitaryan fired wide either side of Reijnders’ tame shot being denied.
The post came to Milan’s rescue twice more to deny Marcus Thuram and Dumfries, before Maignan bravely rushed out to stop the latter.
Inter refused to be defeated, though, and debutant Nicola Zalewski chested the ball back for De Vrij to instinctively turn home, extending Inter’s unbeaten run in Serie A to a current league-high 17 matches.
While not being a defeat for Milan, conceding so late is another bitterly disappointing blow following their midweek loss to Dinamo Zagreb.