AC Milan drew for the first time in Serie A this season as they were held 0-0 at coach Vincenzo Montella's former club Fiorentina.
The Rossoneri had the chance to move above rivals Inter and into the top three with a third consecutive win, but instead found themselves on the back foot and thankful to the woodwork for keeping out Josip Ilicic's penalty.
Davide Calabria's first-half foul on Borja Valero led to the game's best opportunity, but Ilicic smashed against the post from 12 yards as he missed from the spot for the first time in his Serie A career.
Montella, who spent three seasons in charge of Fiorentina, drew in Florence while at the Sampdoria helm last term and was perhaps fortunate to escape with a point again.
Carlos Bacca had netted crucial goals in each of his side's prior victories, but the Colombian cut an isolated figure as the Viola monopolised possession for long periods.
Fiorentina are still yet to concede at home this season and rarely looked in danger of seeing that record altered, despite Milan's recent triumphs over Samp and Lazio.
Montella named an unchanged side from that which cruised past Lazio in midweek, but it was the hosts who had the first attempt as Federico Bernardeschi flashed a left-footed strike over the crossbar.
From a similar position on the edge of the area, Ilicic whipped a shot past the post and Milan Badelj then blazed over as a half-cleared corner fell at his feet.
M'Baye Niang should have punished Fiorentina for their wastefulness when his own effort deflected back into his path, but from close range on the left of the box he likewise could not keep his finish on target.
But Paulo Sousa's men were soon back on the attack and should have led with 23 minutes played.
Badelj's stunning pass set Ilicic away on the right, and from his cross, Calabria tugged Valero to the ground after the Spaniard and Nikola Kalinic had both failed to get a shot away.
Ilicic took the resultant spot-kick, rattling against the foot of the goalkeeper's left-hand upright.
The next opening did not arrive until the start of the second half, with Valero finally finding the target as Gianluigi Donnarumma clung on with ease.
A rare Milan break then sent Niang, Bacca and Suso all flying forward, but a mix-up in the middle saw the latter two get in one another's way and the chance was quickly gone.
The visitors' newfound attacking ambition was leaving space at the back, though, and Donnarumma had to get down to block Kalinic's drive after Ilicic's burst.
Ciprian Tatarusanu made his first stop from Mattia De Sciglio's long-distance effort, before Suso was also denied when he fired low after an elongated one-two with Giacomo Bonaventura.
In an increasingly boisterous atmosphere, Valero was now carrying Fiorentina's chief threat and forced a fine save from Donnarumma at full-stretch with a curler from the right.
Kalinic's bobbling attempt was gathered by the goalkeeper, too, and, despite a frantic tempo and a desperate penalty appeal when Luiz Adriano took a tumble at the death, neither side could force a late winner.
Key Opta Facts:
- Fiorentina are unbeaten in their last four Serie A home games and have not conceded in that run.
- Milan had a 38 per cent possession rate, the lowest for the Rossoneri this season.
- Josip Ilicic had scored eight penalties in Serie A before Sunday's miss.
- Carlos Salcedo marked his Serie A debut by making the most passes in the game (94).