"We fully expect to repeat the performance and victory we got at home to Chelsea and take all three points off United," said the Liverpool goalkeeper.
"Collectively, United are playing so much better than last season. I don't know why, but perhaps it is the return of Paul Scholes that made the difference and the form of Cristiano Ronaldo. They give United great balance.
"Edwin van der Sar is a big part of their success, he is so consistent and one of the best keepers in the world.
"We won't give up on the title until it's mathematically impossible but we aren't preoccupied with it, we're just concentrating on winning the United game."