Tammy Abraham's stoppage-time equaliser completed a remarkable fightback from Roma in a 2-2 draw with Milan, dealing a blow to the champions' hopes of retaining the Serie A title.
Milan appeared to be cruising to victory when substitute Tommaso Pobega followed up Pierre Kalulu's first-half header with a second goal 13 minutes from time, at which point Roma had failed to conjure anything resembling a genuine chance.
However, Roger Ibanez nodded in a powerful header against the run of play after 87 minutes, prompting a late flurry in which Abraham reacted fastest to a rebound from another set-piece at San Siro.
A sole point saw Milan lose valuable ground in the title race, seven points behind Napoli after the Scudetto favourites successfully protected their own 2-0 advantage against Sampdoria earlier on Sunday.
With Jose Mourinho watching on from afar as he served a touchline ban, Roma started slowly and fell behind after half an hour – Kalulu beating Rui Patricio with a downward header from Sandro Tonali's corner.
It remained one-way traffic after the break, with Theo Hernandez seeing a fierce drive unconvincingly parried by Patricio before Olivier Giroud headed straight at the goalkeeper.
Milan finally had the two-goal cushion they deserved when Pobega took Rafael Leao's pass in his stride before beating Patricio with a deflected left-footed finish.
However, just as the Rossoneri seemed certain to again close within five points of Napoli at the summit, Ibanez halved the arrears from Lorenzo Pellegrini's corner, and there was to be one final twist to come.
A deep free-kick saw Nemanja Matic force a reaction stop from Ciprian Tatarusanu with a close-range header, but Abraham pounced to hammer high into the net, denying Milan a crucial victory at the last.
What does it mean? Another twist in competitive title race
It may be a cliche, but every match really does resemble a final for Milan at present, with Napoli setting an unforgiving pace at the top of Serie A and Juventus suddenly emerging as Scudetto contenders with a run of eight consecutive wins.
Stefano Pioli's champions handled the pressure well for much of Sunday's game, but their late capitulation could cost them – Milan last failed to win a Serie A match when holding a two-goal lead after 85 minutes in October 2009 against Napoli.
Roma's dead-ball work pays off
Roma's lack of creativity looked set to cost them dearly on Sunday, with the Giallorossi failing to record an attempt on target until Ibanez's goal.
However, the visitors' set-piece expertise made the difference. A huge 48 per cent of their Serie A goals this season have now come from such situations (10 of 21), the biggest share in the division.
Tonali pulls the strings
Although Milan will be gutted to have thrown away two points at the last, one major positive was the performance of Tonali, who teed up Kalulu's opener as part of a composed display.
The midfielder has now been involved in four league goals (one goal, three assists) since the start of November. Over the same period, only Marcus Tavernier (five), Youcef Belaili and Martin Odegaard (both six) have bettered that tally across Europe's top five leagues.
Key Opta Facts
– Leao is one of three players to have scored at least five goals and provided at least five assists in Serie A this season (also Khvicha Kvaratskhelia and Nicolo Barella).
– Pellegrini has provided the most assists from set-pieces in Europe's top five leagues in 2022-23 (four).
– For the third time this season, Roma had no shots on target in the first half (also against Napoli and Torino).
Both sides will turn their attentions to the Coppa Italia in midweek, with Milan hosting Torino on Wednesday and Roma welcoming Genoa to the Stadio Olimpico on Thursday.