United came from behind to win 2-1 at Selhurst Park on Sunday.
“It was massive,” Fernandes told MUTV. “We needed the three points after the performance and the result we had last week.
“We needed a response very quickly. I think first half was not great for us, but the second half was a very big response.”
Josh Zirkzee struck to cancel out Jean-Philippe Mateta's opening Palace goal from the penalty sport.
“It’s important for every player to score,” Fernandes continued. “Strikers want to score goals, want to have their chances, but it’s not only about that, Josh gives very different things to the team when he doesn’t score.
“We’re very happy because we know how much of a boost of confidence it will give him to try more and get more chances to shoot, because he’s very capable of it.”
After Mason Mount's winner, Lisandro Martinez made a late substitute's appearance - a first since his February knee injury.
Fernandes added, “It’s very important to have him back, it’s such a long spell that he was out, even for himself, it’s great to be back with the team to have this feeling of playing games again.
“We know how much he struggled being out without being able to play for us. He’s back and one more option to have such big quality in the team, so we’re very happy with it.”