Serie A's Milan giants gained crucial ground on Napoli after the league leader threw away a two-goal lead to draw 2-2 against Sassuolo on Wednesday.
Luciano Spalletti's side looked set to maintain its three-point lead at the top following second-half strikes from Dries Mertens and Fabian Ruiz.
But a superb finish from Gianluca Scamacca with 19 minutes remaining put the host back in the game and Gian Marco Ferrari snatched a draw in the final minute with a bullet header.
AC Milan is just one point back in second and Inter Milan another point behind in third following their respective wins over Genoa and Spezia.
Sassuolo thought it had won it in a frantic finale in which Spalletti was sent off when Gregoire Defrel slotted home.
But with the home players and fans celebrating wildly, the referee was called to check a Domenico Berardi foul on Amir Rrahmani and the goal was ruled out.
"It would have been a shame not to draw a match that I think we played on equal footing with Napoli, we kept playing at 2-0 and we deserved to draw," said Sassuolo coach Alessio Dionisi to DAZN.
To make matters worse for Napoli, who was already without Victor Osimhen and Andre-Frank Zambo Anguissa, it lost Ruiz and defensive lynchpin Kalidou Koulibaly to muscle injuries, and Spalletti suggested the pair would not be available for the visit of high-flying Atalanta.
"He (Ruiz) is having issues as is Koulibaly," he said to DAZN
"It'll be difficult to get them back in time, but we'll see because we have good doctors here."
Milan took full advantage with its 3-0 stroll at Genoa despite starting center back Simon Kjaer being stretchered off early with a knee injury, while Inter ran out 2-0 home winner over Spezia.
Junior Messias continued his incredible rise with a brilliantly taken brace on either side of halftime at the Stadio Luigi Ferraris after Zlatan Ibrahimovic had curled in a perfect free kick to give Milan a 10th-minute lead.
Brazilian Messias, a 30-year-old former fridge deliveryman who is only in his second-ever Serie A season, looped in a distance header in first-half stoppage-time to double the away side's lead before rolling home a delicate finish in the 61st minute to ensure the win following straight league defeats to Fiorentina and Sassuolo.
His double comes after he struck the winning goal at Atletico Madrid which keeps alive Milan's hopes of making the Champions League last 16 ahead of the visit of Liverpool next week.
"What happened in Madrid is the past and what's needed now is consistency," Messias said to DAZN.
"We've struggled and lost points recently so it was important to win and play well."
Roberto Gagliardini and Lautaro Martinez struck in each half for Inter at a freezing San Siro as Simone Inzaghi's side extended its unbeaten run in all competitions to 10 games.
The win was its fourth on the bounce with a much-changed lineup as Inzaghi shuffled his deck with a host of defensive injuries and a trip to Roma coming on Saturday.
Spezia has conceded a whopping 34 goals in 15 games and was brushed aside by an Inter side which was without several starters and in second gear for much of the night.
Bologna is eighth, level on 24 points with Juventus and Fiorentina after Mattias Svanberg fired his side to a 1-0 win over Jose Mourinho's Roma.
Swede Svanberg struck a beautiful winner from distance to move Sinisa Mihajlovic's side to within one point of fifth-placed Roma.
The result is also great news for Atalanta, who after its win over Venezia on Tuesday is six points away from its nearest challenger for fourth and the final Champions League spot.