"It's been a very good day for us really," Alex Ferguson told Sky Sports. "We had to work hard for this victory.
"The rain was never-ending and it made the pitch a bit sticky and difficult to move the ball at times.
"Reading are a really good side and make you play for the whole 90 minutes and their delivery into the box was very good.
"Today was our worst defending of the season. It (the second goal) was a slack goal for us to lose.
"It could have been a softish foul, but we should have reacted better than that."
Ferguson was full of praise for match-winner Ronaldo, who has now scored six goals in his last three Premiership appearances.
He added: "There is no question he is maturing all the time and he is getting experience of playing football all the time.
"He has got all the materials to be a really fantastic player and he has shown that this season.
"His consistency, his work rate and his playing for the team has been excellent."