Jose Mourinho's Red Devils conjured only a few shots on goal in the eventual 0-0 draw suggesting to former City midfielder Lampard that they set themselves up simply to gain a point from the Manchester derby.
He told Sky Sports: "I'm slightly surprised. We did feel that he (Mourinho) was going to defend deep. They definitely played for that.
"They didn't overcommit players at any stage. I think Martial played like a left-back at times.
"When you look at the table, maybe you see why they played for it, as the top four is in their hands still.
"I don't think Mourinho wanted to go toe-to-toe with Manchester City tonight. He looked at the bigger picture. They got the result they wanted, and they're happy in the dressing room, for sure."