The Red Devils were unable to haul themselves back into the game after the hosts stormed into a two-goal lead via first-half goals from Semi Ayaji and debutant Nobel Mendy at the MKM Stadium.
Michael Carrick looked to calm fan frustration at full-time by insisting one poor result will not change his approach for the months ahead as club captain Bruno Fernandes admitted the team are still making the same mistakes they did in away games last season.
The opening goal was a particular concern for Carrick as United missed several chances to clear a ball into the box before Ayaji eventually fired home.
That poor defending was seized on by former United No.1 Peter Schmeichel who called out several defenders for not being strong enough to deal with the situation.
"Look at Dorgu on the front post, he's not even looking at the guy taking the corner,’ the United legend told Premier League Productions.
"At that exact moment, he loses his concentration, he does not have the ability to block the first ball.
"And of course, Ayden Heaven on the back post. He allows McBurnie to go behind him. You can’t allow that. That’s not how you defend, you have to be stronger.
"It's the absolute lack of concentration from Man United. That’s what disappoints me the most."