Don't forget it's at Old Trafford, the first goal is everything in this clash, the players know they HAVE to perform, this is top four they are fighting for, Liverpool the title, it's going to be one of those games, make or break, the players know it.
Rooney, Fellaini, Mata, van Persie, all 4 players who can win games one way or another, be it by sheer brilliance, or muscle, it's confidence, Jones and Smalling against Suarez and Sturridge.. that could decide the game.
It's not an impossible feat, Moyes may throw a wild card, start Januzaj in CAM, say "Januzaj, Touré is known to be error prone, I want you to run at him as much as possible today, make him make a decision", there is weakness in that Liverpool side, I'd be exploiting Touré all day if I was the players, if a team has a weakness you exploit it.
Equally Rodgers can just pack the midfield, rely on brilliance of Suarez to win them the game, Manchester United won't won the midfield battle, the midfield isn't good enough, so it's stick or twist, being a manager at Manchester United you have to make some tough choices, it's not about picking big names, it's about selecting the right squad for the job.