The vice-captain of the Catalan outfit has been missing for a few weeks with a hamstring injury, but has shook off his knock to feature in the match in Italy from the start.
Assistant coach Jordi Roura has named a very strong starting line-up for the first leg of the European tie. Carles Puyol and Gerard Pique are the the first-choice central defensive pairing, with Dani Alves and Jordi Alba featuring alongside.
Sergio Busquets and Cesc Fabregas make up the midfield trio with Xavi, while Pedro and Andres Iniesta are the men partnering Lionel Messi in attack.
Milan will be frustrated that it cannot call upon Mario Balotelli this evening. The new signing for the Rossoneri is cup-tied as he featured for Manchester City in the group stage prior to his transfer in January. Giampaolo Pazzini comes in to replace him alongside Stephan El Shaarawy up front.
Kevin Prince-Boateng plays in a more advanced role just behind the strikers, with Ricardo Montolivo, Massimo Ambrosini, and Sulley Muntari sitting in midfield.
AC Milan (4-3-1-2): Abbiati; Abate, Mexes, Zapata, Constant; Montolivo, Ambrosini, Muntari; Boateng; Pazzini, El Shaaraway.
Subs: Amelia, Yepes, De Sciglio, Cristante, Traoré, Bojan
Barcelona (4-3-3): Valdes; Alves, Pique, Puyol, Alba; Xavi, Busquets, Cesc; Pedro, Messi, Iniesta.
Subs: Pinto, Montoya, Mascherano, Song, Thiago, Alexis, Tello