The midfield terrier was given a standing ovation by the Red Devils faithful after playing a key role in a 3-0 win over Ukraine on his first start for his country.
Ferguson said: "He did alright, didn't he?
"Nico's got potential to play at the highest level but he needs to understand that he's still got a few things he has to work on and has to learn.
"If he does that then what a chance he's got. He's 24. His best years are still in front of him.
"Since I've come in he's been top class for me but he has to continue that. It's great to see him get his first start. I was absolutely but now it's delighted about bettering that.
"He comes back here but he has to produce the performances for me and I'm sure if...