Ferguson is not underestimating the task he faces against the Canaries.
After all, they were the last team to beat United in the league when they won 1-0 at Carrow Road in November.
Fergie said: "This is an important one for us because Tuesday will look after itself, there is no doubt about that. It's an occasion on Tuesday.
"Today is the mundane, practical situation; we need to win because it is an important league game.
"That is what our concentration is on. I can assure you, the players will not be thinking about Tuesday at this moment because all week we've been talking about how important Norwich is.
"The league games are more important because we don't want to give our immediate opponents an advantage.
"That accentuates it more for me and is why I place so much importance on Norwich because it's a game we must win."