Key to beat Barcelona: how to prevent Barce getting 70% possession. Ans: Use young players with good stamina to run all over the park to win the ball.
So leave out slow & old players like Giggs (he can't play anyway due to media storm), Rio & Carrick.
Smalling takes over from Rio in defense which also has fast players like Rafael, Evra, Vidic.
Need Fabio to mark Messi all over the field. Park to run all over midfield to win balls. And there is Valencia and Nani to provide width & feed the final ball to Rooney & Chico.
And of course, Edwin in goal.