Cesare Maldini: Milan must forget first leg loss
Despite taking an early lead at the San Siro on February 16 through Ronaldinho, Leonardo's side trail 3-2 heading to Old Trafford following Paul Scholes's leveller and a headed double from Wayne Rooney.
Milan must now score at least twice in Manchester on Wednesday if they are to eliminate the Premier League champions, who have reached the last two Champions League finals.
And Maldini, who made 347 league appearances for Milan before briefly managing them on two seperate occasions in 1973 and 2001, believes the Rossoneri must appraoch the second leg against Sir Alex Ferguson's side as if the aggregate score is 0-0.
"I have positive feelings even though it will not be easy as Manchester United are one of the best teams in the world," he told Tuttomercatoweb.com.
"I think we will see a great international clash as both teams like to attack.
"But they must put the first leg in the archives and think about this game. What happened has happened and it doesn't matter."