Keisuke Honda marked his full Milan debut with a goal, as the Rossoneri began life after Massimiliano Allegri with a comfortable victory. Robinho and Giampaolo Pazzini also got on the scoresheet, while Nicola Ferrari netted a late consolation for the visitors. Milan will now face Udinese in the last eight of the competition.
In the wake of Allegri's sacking, Caretaker manager Mauro Tassotti picked the team, with Clarence Seedorf assuming control from tomorrow.
Honda and fellow January buy Adil Rami were given their first starts, while Pazzini continued his comeback from long term injury. Serie B's Spezia had ousted Pro Patria, Genoa (on penalties) and Pescara en route to this glamour meeting at the San Siro. Devis Mangia's side are currently 12th in the Italian second tier. Pasquale Schiattarella was handed a debut, following the midfielder's arrival from Livorno.
Unsurprisingly, Spezia's Nicola Leali was the busiest of the two goalkeepers. He showed strong hands to block a Cristian Zaccardo effort at the back post. However, his opposite number Christian Abbiati looked shaky when he came to punch clear a free kick and needed the Milan defenders to bail him out.
Philippe Mexes sent a long distance effort over, before Pazzini swept an effort wide from point blank range. Honda's free kick was floated into the box and nodded down into the frontman's path, but he couldn't capitalise. Pazzini remained in the thick of the action. He collected a backheel from Andrea Poli and shaved the top of the crossbar with a powerful drive from the edge of the area.
Milan took the lead on 28 minutes. Pazzini turned provider to cross for an unmarked Robinho to guide a diving header into the net. Three minutes later, Pazzini finally got the goal he was craving. Poli lifted a ball into the box and the forward let it drop before connecting with a sliding volley into the bottom corner.
Riccardo Montolivo kept his wits about him to head an Andrea Bovo effort off the line and into the air to safety.
Honda managed to grab his first goal in front of his new fans just two minutes after the restart. Leali could only parry Montolivo's long range effort, allowing Honda to lift the rebound over the fallen shot stopper. Pazzini should have made it four moments later. He timed his run to collect Honda's through ball, only to balloon his effort into the stands.
Milan were laying siege to the visitors' goal. Leali kept out Mattia De Sciglio's effort, but the ball crept underneath him for a corner. From the delivery, Honda spun past his marker and curled over the bar. A last ditch Andrea Lisuzzo tackle prevented Zaccardo from getting in on the scoring.
Honda departed the game just as Seedorf was taking his seat to see his new side up close. Pazzini fluffed his lines again from close distance, then headed straight at Leali. On any other day, Pazzini would have had a hat trick. The forward was applauded off when he was replaced by teenage striker Andrea Petagna.
Spezia's travelling support were given something to cheer in stoppage time. Abbiati got his hands to a Francesco Migliore snapshot, but the ball was played back into the box and Ferrari turned it in at the second attempt.
AC Milan: Abbiati; Zaccardo, Mexes, Rami, De Sciglio; Poli, Montolivo, Cristante; Honda, (Birsa 64) Robinho; (Nocerino 78) Pazzini (Petagna 71)
Spezia: Leali; Baldanzeddu, Bianchetti, Lisuzzo, Migliore; Seymur, Bovo; Schiattarella, (Culina 61) Catellani, (Orsic 85) Rivas; (Ciurria 76) Ferrari
Goals: Robinho 28 (M) Pazzini 31 (M) Honda 47 (M) Ferrari 91 (S)