A giant killing was narrowly avoided on Tuesday night as AC Milan met Crotone in a fourth round Coppa Italia match at San Siro.
Visitors Crotone only avoided relegation to the third tier of Italian football via a play-off last season, but in a remarkable turnaround sat second in Serie B heading into the big tie with Milan.
Meanwhile, the Rossoneri will have been full of confidence after their demolition job of Sampdoria on Saturday night, beating Montella's side 4-1 thanks to goals from Giacomo Bonaventura, M'Baye Niang and Luiz Adriano.
Not ones to be fazed by the occasion, Crotone set up in the familiar 3-4-3 formation with Giuseppe Torromino, Raffaele Palladino and Pietro De Giorgio leading the forward line for Ivan Juric's side.
Milan used the opportunity to rotate the squad, fielding a front three of Suso, Luiz Adriano and Keisuke Honda. Mihajlovic was also able to call upon young prospects Davide Calabria and Jose Mauri as Milanisti got a glimpse of the future.
Underdogs impress in goalless first half
Crotone, in their first visit to San Siro, were represented by a huge away following numbering in the thousands. They were allocated the first tier, a rarity in Milan.
However, they begun the game nervously, allowling Suso to cut inside from the right and unleash a second minute shot that whistled over.
In the tenth minute, Luiz Adriano was allowed space inside the area to head a Zapata cross towards the far corner, but his looping header landed wide of Cordaz' post.
Palladino thought he had got through on goal for the visitors, though upon scuffing his shot into Abbiati's arms the flag was raised.
Crotone had a half chance to take the lead again in the 20th minute when Torromino forced Abbiati into a fingertip save to deny an effort from just outside the edge of the box.
Luiz Adriano shot from the same location in the other half moments after, however his shot trickled to the 'keeper.
The visitors had a huge chance in the 25th minute when they cut Milan open down the left side, taking advantage of an out-of-position Calabria. Eventually, a pullback found De Giorgio who sidefooted an effort that Abbiati parried and the ball was cleared. A moment of panic without doubt for the men in red and black.
Milan struggled to assert themselves on the game, and while they looked dangerous in spells around the box, they had little to show.
Suso almost curled an effort from the edge of the area into the far left corner, yet his effort didn't quite bend in enough and nipped wide. Moments later Nocerino had a shot saved comfortably.
The Spaniard had another shot in the 39th minute, this time a low drive that Cordaz did well to keep out, and Nocerino's follow up somehow ended up wide, though he did have less than a second to react. Exactly a minute later Jose Mauri found space to shoot but put his attempt too central to trouble.
Ante Budimir, who came on just after the half hour mark in place of the injured Palladino, headed wide in the last chance of the break.
Deadlocked at 0-0 with Crotone more than holding their own in this one. Milan's eleven just hadn't really turned up and Sinisa Mihajlovic will have been making it clear that things had to change during the break.
Devils turn it up a gear
With the first attack of the second half AC Milan took the lead.
Luiz Adriano received a through ball from Poli inside the area, and took it around the 'keeper before slotting in from a narrow angle on the right side of the box to make it 1-0 to the home side.
Andrea Poli should have made it 2-0 three minutes later when the ball fell to him on the edge of the box after a semi-cleared cross. Somehow, the midfielder lifted his effort over the bar.
Antonio Nocerino produced a spectacular overhead kick effort in tight space after a cross wasn't cleared, forcing Cordaz to palm behind at full stretch as the hour mark was near.
The beginning of a fairytale?
The San Siro was silenced in the 68th minute as Crotone equalised thanks to a moment of individual brilliant from Ante Budimir.
The man on loan from St. Pauli nutmegged Cristian Zapata before cutting inside and thundering a shot past Abbiati, making the score 1-1 and sending the travelling fans into raptures.
Milan were forced into a double change as Bonaventura and Niang were introduced, two of the stars from Saturday's resounding win.
Budimir was the subject of a penalty appeal for Crotone with ten minute left as he was seemingly barged over by Zapata, but the referee Fabbri ruled he muscled him off the ball and let play continue.
The striker then headed over from around eight yards out as a cross from the right found his free head. If any team was going to win this, it would be Crotone.
However, the tie would have to be settled in extra time as neither side could fashion a winner. Somewhat embarrassing for a sluggish Milan side, though credit must be given to Crotone for what was a wonderful 90 minutes.
A display of disgust
In a staggering statement, Milan's famous Curva Sud left the stadium in protest of the performance they had seen from their team.
Their team had the first opportunity in extra time as in the 95th minute Adriano's cross narrowly evaded Niang at the far post who would have had a tap in.
It was looking like heartbreak for Crotone when Milan converted a 105th minute free-kick.
Niang was brought down on the edge of the box, and Giacomo Bonaventura produced a delightful set piece, curling over the wall and inside the left post to give Milan an undeserved but potenitally decisive 2-1 lead.
The tie was over when M'Baye Niang scored Milan's third late on in extra time, slotting home from a Bonaventura feed and booking the Rossoneri's place in round five.
A performance for Crotone to be proud of, and ultimately on another day they could have won the game in the first 90 minutes, though unfortunately for them they didn't have the legs for extra time.
Milan will be concerned about a lack of ruthlessness, and even though they came through the game they made things far too difficult for themselves.