1 They know what it feels like to get a score draw at Camp Nou, and they did it this season. Despite the fact Barca dominated the group game, it ended 2-2. That result would see the Italians through here.
2 Alexandre Pato (right) scored Milan's opener in that 2-2 draw and he is fit again after a month's lay-off. If Robinho fails to deliver as he did in the first leg, Pato will give Massimiliano Allegri options from the bench.
3 Lionel Messi (right) may be one goal from becoming the first player to score 13 times in one Champions League season and two away from matching the all-time European Cup record, but Barca's all-time top scorer has a poor record against Italians. Messi has played seven Champions League games against them and scored just once. Milan are also the only side in the last 10 to have prevented him scoring.
4 Zlatan Ibrahimovic has a point to prove and this is the place to do it. The Swede cost almost €70m (£58m) in 2009 but the most expensive player in Barca's history was never going to be more important than his strike partner, who cost nothing. Tonight the Swede can finally get the better of Messi.
5 Milan have never gone out of the European Cup after drawing 0-0 at home in the first leg. Three times they have shut the opposition out at home without scoring and progressed each time. They also play the holders knowing no side has been able to retain the European Cup in its present format.