The Reds, who haven’t lifted the trophy since 2004, travel to London following a packed festive fixture list in which United won three games, drew one and stretched the lead at the top of the Barclays Premier League to seven points.
Sir Alex used 19 different players over that period and has promised he’ll continue to utilise his full squad for this weekend’s FA Cup fixture.
“We'll make a few changes for the cup tie,” the manager told MUTV. “Obviously, the likes of Evra and Carrick – who I took off in the second half as soon as we got the third goal – probably deserve a break.
“They've been playing all the games so we'll have a look at the situation.
“We've got fresh players, though. Young Shinji Kagawa came on against Wigan and Tom Cleverley is fresh as he's not had a lot of football – he’s shown a great appetite just now, though.
“We've got plenty of players we can freshen up with.”