United host the Reds at Old Trafford this weekend.
McClair told manutd.com: "The only real rivalry has been at first-team level. At other levels of development football, including the Reserves and Under-21s, yes, there's competition but it's much more amiable in the whole time I've been involved. We have a good relationship with Liverpool at Academy level, even though they've changed their set-up a little in the last few years.
"For the first team, it's a fierce rivalry. When Sir Alex first came down to Manchester, he always said he considered that to be our biggest game. I remember him saying that if we finish above Liverpool we'd win the league. That tells you a lot. What sets this fixture apart is the supporters - there's so such passion and will to win. You want to win all your games but this one in particular means so much to the fans."
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