Smith got his calculations right and his side stopped United from breaking through a tight defence, keeping the main danger down to long range efforts from Darron Gibson.
Smith told UEFA.com: "We are obviously pleased to get a point in our first Champions League game. We worked very hard for it.
"The boys showed great concentration and limited United to long-range shots. I'm proud of the way my players played.
"We were not very tidy in possession at times, but I'm obviously happy with a point.
"With more care we could have created more but we expected to come here and defend and we did that well.
"The game was as I thought it would be. We tried to nullify them and we managed to do that. In the Champions League you have to do that."