AC Milan coach Carlo Ancelotti needs no reminder that Manchester United, today's Champions League opponents, are capable of winning against the odds in Italy.
Six years ago Ancelotti was coach of the Juventus side who earned a 1-1 draw at Old Trafford only to lose the second leg of their semi-final 3-2 at the Delle Alpi stadium.
Milan went one better than Juventus in the first leg of their knockout round match last month, winning 1-0 in Manchester, but Ancelotti is taking nothing for granted.
"I remember extremely well what happened last time....we know the job is only half done," he said at Old Trafford.
United manager Alex Ferguson says victory over Milan would be an even greater achievement than the upset at the Delle Alpi.
"Turin was the greatest performance of my time here, easily," he said. "To win on Tuesday would be above that. Milan's experience at the back is the thing."
Caution and cool defending are likely to be Milan's watchwords at the San Siro. Ancelotti's team know a draw would be enough to see them through although the coach insists that will not mean a negative approach.
"We don't want to simply defend because that can end badly," he said. "Rather we want to play as we did in Manchester."
The Italian champions are on a run of excellent results which underline the tightness of their defence.
After two defeats in January, Milan have won their last seven games -- four of them 1-0. On Saturday they beat Atalanta 2-1 courtesy of a final second winner from midfielder Andrea Pirlo.
Injuries and the need to rest players ahead of Tuesday meant Ancelotti shuffled his pack. Striker Filippo Inzaghi and former United defender Jaap Stam made their returns from injury and could play some role in Tuesday's game.
Inzaghi is set to start on the bench, a boost for Ancelotti who is likely to be without Ukrainian Andriy Shevchenko after suffering a fractured cheekbone last month.
Milan will have to wait for a fitness check on Georgia left back Kakha Kaladze. If he misses out then Giuseppe Pancaro is on stand-by.
United were frustrated by 10-man Crystal Palace at Selhurst Park on Saturday and will need to find greater penetration if they are to trouble Milan.
Dutch striker Ruud van Nistelrooy, who made his return from injury in the first leg, is still short of full match fitness and so Wayne Rooney will probably be given the nod to start in attack against Maldini and Alessandro Nesta.
Keeper Roy Carroll, whose error handed Hernan Crespo the chance for Milan's goal at Old Trafford, has been dropped in favour of American Tim Howard.
Ferguson will re-shuffle his defence after England's Gary Neville was ruled out by an ankle injury, his place at right back probably going to Wes Brown with France's Mikael Silvestre slotting into the middle.
Rooney's pace and the threat on the wide threat of Cristiano Ronaldo could trouble Milan's ageing back line, though French striker Louis Saha is out through injury.
Ferguson is banking on his side's experienced core to deliver.
"Tuesday's going to be a night for the big players," he said. "We'll have to defend better than we've ever defended.
"If we don't lose a goal, the longer the game goes on, the better our chance may be. I think the team who wins this tie could go on and win the cup.
"I know there are some other good teams, particularly Barcelona, but there's a great mental toughness about us and Milan," said the United manager.
AC Milan: 1-Dida; 2-Cafu (or 31-Jaap Stam), 13-Alessandro Nesta, 3-Paolo Maldini, 4-Kakha Kaladze; 8-Gennaro Gattuso, 21-Andrea Pirlo, 20-Clarence Seedorf; 10-Rui Costa, 22-Kaka, 11-Hernan Crespo.
Manchester United: 1-Tim Howard; 6-Wes Brown, 5-Rio Ferdinand, 27-Mikael Silvestre, 4-Gabriel Heinze; 7-Cristiano Ronaldo, 16-Roy Keane, 18-Paul Scholes, 25-Quinton Fortune, 11-Ryan Giggs; 8-Wayne Rooney.
Referee: Herbert Fandel