United fans will not expect a repeat of the stunning 7-1 demolition of AS Roma in the quarter-finals and will remember the last time Milan visited Old Trafford on their way to the 2005 final which they lost to Liverpool.
Milan had lost seven of nine games in England and not recorded a single victory until a 1-0 win over United in Manchester in the knockout stage.
Premier League leaders United are without Rio Ferdinand, Gary Neville, Nemanja Vidic and Mikael Silvestre, while French full back Patrice Evra is doubtful.
United, at least, can welcome back Paul Scholes after the midfielder missed the Roma demolition through suspension. Scholes will need to keep a check on his aggression though, with one more yellow card earning another ban.
"Most importantly, we want a clean sheet. That's first and foremost," defender John O'Shea told Manchester United Radio.
"Obviously any victory -- 1-0 or 2-0 -- would be ideal because we know we're more than capable of scoring away from home. The attacking form of the team this season has been immense."
Milan go into the tie in good form with five successive wins, including an impressive 2-0 victory at Bayern Munich in the second leg of their quarter-final which sealed their last four place.
