With the draw having been made 24 hours ago, both sides go into tonight’s game knowing a home tie against Middlesbrough or cup holders Chelsea awaits.
With United still fighting on three fronts, Sir Alex had already confirmed there would be changes from the side who faced Real Madrid in the Champions League last week but made his feelings known that he is taking this cup very seriously.
The last time United faced Reading was just over two months ago in a thrilling 4-3 encounter which saw all seven goals scored in the first half.
Having overcome Premier League opposition in West Ham and Fulham, United hope to keep the FA Cup dream alive.
De Gea, Smalling Jones Vidic Buttner, Valencia Anderson Cleverley Young, Hernandez Welbeck