United won the match 2-0 after goals by Wayne Rooney and Cristiano Ronaldo.
Ferguson said: “We had a number of chances in last third but we started to worry that we weren’t going to get the goal.
“Credit to Reading who never stopped working and really made us work.
“It was a really open match. Our own attacking play wasn’t at it’s best and more care was needed up front. We scored at the right time and held on.”
