United went out on away goals in the second leg of that Leverkusen match and, strangely, it is a decade since they won a European knockout tie in which the first leg was at home; even then they had to win in Juventus to go through. Since then they have played 14 knockout ties; in only four of those did they play at home in the first leg, and they went out each time.
Full article here:
http://www.guardian.co.uk/football/blog/2009/apr/07/manchester-united-porto-champions-league