Lindegaard
Jones - Smalling - Vidic - Buttner
Anderson - Cleverley
Nani - Kagawa - Young
Hernandez
Lindegaard needs some game time whilst De Gea needs a rest so I think its likely that Anders will start on Monday. I'd give Rafael a rest as he's played a lot of football recently and could do with a break, with Jones (who's been playing well recently) coming in to fill in at Right Back. Smalling and Vidic would come in for Rio and Evans in order to give the latter pair a rest (and get Nemanja more game time on his road to recovery) with Buttner replacing Evra as has been the case for most cup games this season.
I'd like to see Ando and Clev in midfield, it would bring a lot of energy and creativity to the team and against a vulnerable Reading side, that will be crucial in creating chances. On the wings, I'd play Nani and Young. Both are in need of games and have a point to prove so I can definitely see them starting this one.
I believe that Kagawa should play just behind the striker, his preferred position and one he hasn't played in often this season for a variety of reasons. It'd be nice to see how he does their and against defensively weak opponents, he could be very effective in this game.
Hernandez will most likely start up front as Welbeck, van Persie and Rooney have played a lot of games recently and could do with a rest whereas Chica hasn't started a game for a while now.
I'm sure the likes of Giggs and Scholes will come on if we are winning comfortably and this could be a great chance to rest a few players (RVP etc) and also give others some sorely needed game time. Reading are a decent side and will give us a good game, but we should be to strong for them and I reckon we'll win 3-1 (Hernandez, Anderson and Nani with our goals).