With the domestic campaign bubbling nicely, United are here to complete a job all but finished at Old Trafford a fortnight ago. The catchphrase is "beware complacency" but few expect the 4-0 first-leg lead to be overturned. A semi-final with Borussia Dortmund or Auxerre is being contemplated.
Not that United, who will have two spies in Auxerre tonight, are taking Porto for granted. When asked if he had previously had to defend a 4-0 lead, Gary Pallister paled. His voice dropped to the same low tone Allan Border always used when discussing Headingley 1981. "I've seen some terrible things in cricket," Border would say, when faced with apparently certain victory.
Pallister's nemesis was in Barcelona two seasons ago. United were humbled 4-0 and Pallister recalled: "We took a lot of stick.
"I've never been in this position but I know if you are not professional the roof can cave in. The Nou Camp was not so long ago, we are all aware of that. No one at Old Trafford needs reminding of that night. Coming back from Barcelona we felt embarrassed - Porto would have been the same after Old Trafford."
United are expecting an early assault from Porto, whose pride was further dented by a home defeat to Sporting Lisbon at the weekend. After being unbeaten all season, they have now lost three and won one of their last five matches. Antonio Oliveira, Porto's coach, has refused to speak to either the local or foreign press or allow them into his training sessions. This reflects the mounting pressure on his position - another humiliation tonight and he could be sacked, even though Porto still lead the Portuguese League by seven points.
Ferguson is more concerned with his players' welfare. Ryan Giggs (hamstring), Gary Neville (ankle) and Andy Cole (thigh) are all doubtful, with Cole and Giggs unlikely to start. Any one of several players could replace Giggs, while Roy Keane would come in for Cole with United reverting to four across the middle. The injuries mean he is unlikely to rest Eric Cantona, the most volatile of seven players on a yellow card. United are yet to have a player suspended, Porto have three out tonight: Sergio Conceicao, Rui Barros and Artur.
Portuguese police are expecting up to 10,000 United fans - only 6,400 of them in the official party. So far United supporters have been generally well-behaved in Europe. As long as they continue to be so, United's season should still be glowing with promise tomorrow.
Porto (probable): Hilario; Joao Pinto, Aloisio, Jorge Costa, Fernando Mendes, Barroso, Paulinho, Zahovic, Edmilson, Jardel, Drulovic.
Manchester United (probable): Schmeichel; G Neville, May, Pallister, Irwin, Beckham, Johnsen, Keane, Poborsky; Solskaer, Cantona.