Fernandes created the winner struck by Matheus Cunha for the 1-0 triumph - his 18th assist for the season.
Carrick was full of praise for the Portugal midfielder, who was outstanding on the night.
He said afterwards, “His impact has been immense for a period of time, he's carried that all the way through. He plays most games, he's fit, he's hungry.
"He had a big shift to do in the middle but he was willing to do that for the team. He's a big personality, he's the captain for a reason. Sometimes it's leading by example and showing the way.
"He's vocal, he's a big presence on the pitch. He's been a big part of this club over the last few years.”
The win strengthened United's hold on third place on the Premier League table.
Asked about his own future, Carrick added: “I love being here. I understand the situation, it's a bit out my hands. You want to be parts of nights like this, part of special things, create a team. I haven't got a timeframe.”