Noah Okafor struck after five minutes and doubled the lead before half-time, a second that flicked off Leny Yoro to leave United stunned. Lisandro Martinez's red card for pulling Dominic Calvert-Lewin's hair, confirmed by VAR, compounded a miserable evening, though Casemiro's header gave the hosts brief hope as Fernandes registered his 17th league assist of the season.
The United captain was blunt in his assessment afterwards.
"We gave the game away in the first half," Fernandes told Sky Sports. "We were not up to the game straight away with our intensity. We knew they wanted to press as 1v1, we had to be better on the first ball but even better on the second ball."
He did not spare his teammates. "We weren't great, we gave too much space away. We ended up going 2-0 down, we had time in the second half to turn it around but it was not possible."
The half-time message was simple. "For us to lift the standard on the intensity. To be more aggressive. That's it."
Fernandes was pointed when asked about United's 24-day break between fixtures, a consequence of their early FA Cup exit. "It is what it is. We are out of the FA Cup so we have to blame ourselves to be out of the game for so long. We did prepare in the best way but it wasn't enough to win the game."
On Martinez's dismissal, the Portuguese skipper chose his words carefully — and made clear he was doing so deliberately. "I'm not talking about the referee. If I talk about the referee I'm going to get in very big trouble because the rules are applied differently for everyone. It's better that I don't say anything."
It was a pointed silence that said plenty.
Despite the defeat, Fernandes insisted the top-four target remains intact. "It doesn't change anything that we want to achieve. It's in our hands, we have to win our games, if we do that we'll be in the position we want to be in at the end of the season."
United remain third, but with Chelsea closing and confidence dented, the next few weeks will test whether Carrick's side have the resilience to match their ambition.