The England midfielder said: "The way Manchester United are playing, they always create good chances," said Murphy. "We do too and you have to be refreshed about that aspect of our play.
"But they are conceding; it will be a game of chances and goals which the fans will enjoy."
He added: “They are desperate to win to catch up points on ourselves and Arsenal; we are desperate to win to put an end to the recent bad results in the Premiership.
“There is always extra spice about this game because it’s United and the fact that if we do win it will put us in a far better position than them with regards to points.
“But we haven’t been getting points recently so we have to get back to winning ways, whether it’s against them on Sunday or anyone else. We must make sure we do it, even if it will be that much sweeter because it is United.”
Liverpool’s unbeaten record against United stretches back to September 1999
But Murphy warned: “It will be difficult. Ruud van Nistelrooy is on fire at the moment and even though they have their injury problems, they have players in their side who can hurt you.
“I know the capabilities of their players. Paul Scholes is one of the best midfielders in Europe and if he’s on the pitch with Ryan Giggs, van Nistelrooy and the rest, they have plenty of ammunition to get goals.
“The question mark might be that with Rio Ferdinand and Gary Neville missing, they may be vulnerable at the back.
“But it is down to us to take advantage of that. It’s never easy to do that against any side these days – let alone United.”