Ferguson insists he will keep both Hernandez and Italian starlet Federico Macheda at the club.
The duo impressed for United in the 5-2 win over MLS All-Stars on Wednesday.
“I need to keep Macheda and Hernandez,” said Ferguson. “There was a lot of purpose in the way they played their football.
“To play for a club like this is not just about talent. You need something else and they’ve got something else. I am pleased with that.”
Ferguson believes new signing Hernandez is similar to England striker Wayne Rooney.
“If we are talking about a combination with Wayne, I think we would need to adjust a bit. They are similar types of players,” he added.
“We will assess Hernandez really well and make sure we can bring him to good consistent form.
“There are still little things to do but not a great deal. One he gets used to our training I think he will be OK.”
