Playmaker Xavi has been declared fit to play. The midfielder hasn't featured since the loss to Real Madrid in the Copa del Rey at the end of February, but given the importance of this game he will return to the fray.
Otherwise, Barcelona should be fresh for this game, with the likes of Messi, Iniesta, Busquets, Alba, Pique and Pedro all on the bench at the weekend.
Victor Valdes will return between the sticks after missing Saturday's win over Deportivo through suspension.
Milan have issues up front, where Mario Balotelli is cup-tied and Gaimpaolo Pazzini is out injured after being forced off early on in the win over Genoa on Friday.
Robinho is back with the squad and he could push for a starting spot in attack, though Kevin-Prince Boateng should be alright to play after missing Friday's game, and he will likely make up a front 3 with El Shaarawy and Niang.
Philippe Mexes picked up a knock and went off at half-time at Genoa, but has travelled with the squad to Spain and should start alongside Cristian Zapata in a lineup similar to the one that played in the first leg.
When this draw was made Barcelona were flying and Milan were struggling in mid-table in Serie A, and many would have assumed that the Spanish giants would waltz through to the last 8 of the competition. However, things haven't exactly gone to script; Barcelona have lost 3 of their last 5 games to go out of the Copa del Rey whilst their Champions League hopes hang by a thread.
Milan, meanwhile, have charged up the Serie A table and are now 3rd, and after beating Barca in the first leg confidence is high at San Siro. However, they will know the task they have on their hands here will be far from an easy one.
The last 5 Champions League meetings between the sides at Camp Nou have seen only 2 Barcelona wins, and Milan have only failed to score once. The home side won 3-1 when these teams met just under a year ago but had to rely on 2 penalties for that result. Winning by a 2 goal margin - at least - whilst also aiming to shut Milan out could be too big a task, even for the likes of Messi and co.
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