The England forward, who was left out of the 1-0 win over Fulham for disciplinary reasons, looked in far better spirits away in Denmark in the Champions League.
Involved in Rasmus Hojlund's third minute opener, he could have been forgiven for thinking United were on their way to an easy win.
Erik ten Hag's side went 2-0 up before the half hour mark with another Hojlund effort, but soon everything came crashing down.
Rashford planted his studs into Elias Jelert's ankle, and after being reduced to ten men, United conceded two goals to lose their lead.
Rashford and Jelert were battling for the ball when the Three Lions star missed it and ended up almost taking his opponent out of the match.
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The challenge was missed at first glance, but painful-looking VAR replays showed just how lucky Jelert, who was bleeding afterwards, was to avoid injury.
Rashford, though, wasn't so lucky, quickly receiving his marching orders once referee Donatas Rumsas got a second look.
Rashford could only smile in disbelief, with it being only his second career red card, the other coming in a 2018 Premier League match against Burnley.
There were 13 minutes added time due to a pitch invader and a medical emergency in the stands but the home side needed just nine of them to level the game.
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Former Southampton man Mohamed Elyounoussi pulled one back with a left-footed strike.
Diogo Goncalves made it 2-2 with a penalty after Harry Maguire was adjudged to have handled the ball, although it appeared to strike Raphael Varane's arm moments earlier.