De Gea is now proving his class for United after a difficult start to the season.
"That save at the end was massive," said Carrick. "Without that we could have been out.
"They are the saves that keepers need to make but fair play to David. He didn't have an awful lot to do in general play but it was a terrific effort."
And Carrick also had an answer to those critics who have been so quick to condemn the 22-year-old.
"As a goalkeeper you can't let these things get to you," added the former Tottenham man. "If you make a mistake people are all over you. That is just how it is.
"You have to take the rough with the smooth. He is well aware of that."