Champions League history

  The round of 16 opener, Milan's tight, disciplined display saw their centre midfielders cover a deep-lying and compact defence which left no gaps for their opponents to run through. Critically, this support was not present on Tuesday as Barca were granted space on the edge of the penalty area.
The Italians survived two penalty shouts and a poor Messi header, but the tie's key moments arrived with just over five minutes of the first half remaining.  But their usual zip returned on the vast Nou Camp pitch from kick-off as they started at high tempo.This intensity was rewarded immediately as Messi played a neat one-two with Xavi and finished into the top corner with goalkeeper Christian Abbiati rooted to the spot. The goal was the world player of the year's 52nd of the season, but his first in open play in 10 meetings with Italian sides. The left-back, excellent throughout, showed great endeavour to race up from the back and finish at the far post after he was picked out by substitute Alexis Sanchez's bouncing cross. If the France Under-21 international had managed to get an away goal, their opponents would have had to find the back of the net at least three more times to proceed.Instead, Milan's advantage from the first leg was wiped out moments later as Messi fizzed in an unstoppable shot from 20-yards after Massimo Ambrosini lost possession.
Barca continued on the front foot after the interval and went ahead on aggregate for the first time when Villa finished clinically after he was picked out in the box by Xavi. The goal owed much to left-back Kevin Constant's rash attempt to intercept the  pss before it reached the striker.
The visitors now knew they had to score to stand any chance of progression and head coach Massimiliano Allegri brought on former Manchester City striker Robinho.