United knocked City out of the Cup at Etihad.
"I don't think so, no," Smalling told manutd.com.
"The biggest thing it did was give us a morale boost at a time when people were starting to write us off. Instead of crumbling we went to City and beat them on their home turf, even if we made hard work of it in the second half. Winning that game showed a lot of character."