Marcus Rashford had appeared to find some form again under new manager Ruben Amirom, and was back among the goals in recent weeks.
However, the Portuguese native decided to keep the striker on the bench as they faced Arsenal last night, hoping that the goal-getter would come on and have an impact.
Ultimately, nothing went to plan for the new boss as the Gooners won the game 2-0, with both goals coming from set pieces, and none of his substitutes had the desired effect.
Rashford's lacklustre performance in particular really irked former United captain Roy Keane who was commenting on The Overlap's watchalong.
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"I’ll tell you something, Marcus Rashford’s come on. His general play as a footballer is shocking.
"Watch his header there. Have United’s subs given anything since coming on? Nothing. The subs have done nothing.
"That's rubbish. That's f***ing rubbish, he's just kicked it out of play."
The longer the game went on, the more the Irishman's frustration grew, as he and Gary Neville both sat with disappointed faces throughout the entire second half.
"Manchester United deserve nothing anyway. They were rubbish. You know what happens with United? They fool you, they fool you. They’re not dynamic.
"I’m really disappointed with Manchester United. I thought the players were going through the motions a little bit.
"It was easy for Arsenal. The first half was fine but I was expecting a bit more."
Keane's frustration will have been echoed by many Man United fans who were hoping that the 'new manager bounce' might have given them a competitive edge in this fixture.
With the January transfer window just around the corner, Amirom will be hoping to add some of his own players to the squad that he has inherited, and potentially ship off a few.
