AC Milan booked a Coppa Italia last-16 meeting with Sampdoria as extra-time goals from substitutes Giacomo Bonaventura and M'Baye Niang secured a 3-1 victory over Crotone at San Siro.

The Rossoneri had struggled to break down the Serie B high-flier, which had opportunities to win the game only for Christian Abbiati to make important first-half saves from Giuseppe Torromino and Pietro De Giorgio.

Luiz Adriano put Milan in front just after the break, staying calm to round Alex Cordaz and finish neatly into the open goal after a perfect through-ball from Andrea Poli.

Ante Budimir and Matteo Paro both then missed terrific chances from superb Mihai Balasa crosses as Crotone, second in the second tier, fought hard to pull off a shock.

Budimir made amends by levelling the scores midway through the second half, firing a powerful low shot into Abbiati's bottom corner, and the Croatian striker could have had a penalty towards the end of the 90 minutes when he went down under Cristian Zapata's untidy challenge.

But Bonaventura settled matters just before the interval in extra time, beating Cordaz with a sumptuous 20-yard free kick, before Niang beat Cordaz from close range to seal Milan's place in the next round.

Milan coach Sinisa Mihajlovic made 11 changes from the weekend's 4-1 win against Sampdoria and the first ever meeting between these clubs almost started with a bang as Suso cut inside to shoot, but his powerful effort fizzed off target.

Crotone was more than holding its own, though, and veteran Milan goalkeeper Abbiati made the first save of note on 19 minutes, diving low to his left to deny Torromino before then saving De Giorgio low shot with his legs.

Suso almost scored after being given too much room in the box, but Cordaz made a fine stop with his left leg and Antonio Nocerino could not convert the rebound.

Budimir, on as a substitute for the injured Raffaele Palladino, should have put the visitor ahead just before half-time but he headed Balasa's cross just wide with Abbiati well beaten.

That missed chance proved key as Milan took the lead within two minutes of the restart. Poli was given the freedom of San Siro to slip in Adriano, who rounded Cordaz to slot home.

Balasa delivered another brilliant cross from the left flank for Paro, who got up well but headed over, before Cordaz saved an ambitious bicycle kick from Nocerino.

Crotone's reward for its superb performance arrived on 67 minutes when Budimir turned Zapata on the edge of the box and fired a low shot beyond Abbiati.

Budimir could have won a penalty on 79 minutes when he again got the better of Zapata, but referee Michael Fabbri decided against giving a spot kick against the Colombia defender for bundling the striker over as extra-time beckoned.

On the stroke of half-time in the additional 30 minutes, Bonaventura curled in a delightful free kick after Adriano was fouled on the edge of the box.

Niang, who scored his first Milan league goals at the weekend, then tapped in the third to end Crotone's brave attempt at an upset.