A week on from the sides' tense 0-0 Premier League draw at an empty Anfield, Jurgen Klopp's men head to Old Trafford for Sunday's eagerly-anticipated fourth-round encounter.
Liverpool make the trip along the M62 enduring a rare shaky moment, with Thursday's shock 1-0 loss to Burnley their first home league defeat since April 2017.
The third-round triumph against the youngsters of coronavirus-hit Aston Villa is the only win they have managed in their last six matches in all competitions but Fernandes knows they can bounce back at any point.
"They are not scoring in the last games and it starts feeling like 'oh, they are not playing well'.
"They create, they play, but the other teams are playing better and, as I said before, they have more qualities to play.
"Every team goes there to play maybe without the pressure of the fans. Teams play a little bit more comfortably and, as I say, I think it is a moment.
"We don't have to look at that moment because big teams and big players can show in every moment."
Fernandes is hoping to taste victory against Liverpool for the first time since arriving at United and will be desperate to make amends for missing a fine chance to win last weekend's game at Anfield.
"In the past already I have seen Manchester playing for a long time and I know what that game means for the fans," he said.
"Everyone knows and of course, for us, it means a lot because it is a cup (tie) and it is a chance to put one of the strongest teams who are in the cup with us out, so we have to take that.
"Of course, we have so many teams in the cup in this moment that maybe you can have an easier game than this.
"But if you want to win the cup then you have to beat the biggest teams, so we have a chance now to beat one of the best that is left in the FA Cup."
United head into Sunday's match buoyed by their place atop of the Premier League pile, having won a tough clash at Fulham on Wednesday evening.
Paul Pogba's stunning goal sealed a 2-1 win for Ole Gunnar Solskjaer's men at Craven Cottage, providing a welcome shot in the arm ahead of the cup clash with Liverpool.
"Well, you always recover well when you win so I am ready for the next one," Fernandes told club media, having made his 50th appearance for United.
"As everyone knows, I think without the fans it is harder to play because the teams are playing with a little bit of less pressure, so they can keep the ball, they have more time on the ball, they start playing with it a little bit more.
"Maybe before the pressure of the fans to call them to go forward, and go direct, and all of that stuff, but teams now play a bit more and I really liked the way Fulham played.
"They didn't surprise me because I had seen some games of theirs and I think they have really good qualities.
"They are well trained to be better than where they are in this moment."