Fred specifically defied Ole Gunnar Solskjaer's half-time instructions as Manchester United succumbed to defeat against Paris Saint-Germain.
PSG won 3-1 at Old Trafford after a Neymar brace and goal from Marquinhos.
With RB Leipzig beating Istanbul Basaksehir, it means all three teams are on nine points going into the final match.
It means United must go to Germany and avoid defeat against Julian Nagelsmann's team to qualify.
But they will have to do so without Fred, who was sent off against PSG in the second-half.
However, many believe he should have received his marching orders in the first-half when he headbutted Leandro Paredes.
VAR was involved but the referee only dished out a yellow card, while another coming-together between the two South Americans saw Paredes booked when Fred could have easily seen red again.
With such a target on his back, the smart action would have been to take off the 27-year-old but Solskjaer persevered.
And just seconds after going a goal down, Fred was sent off for a challenge on former United star Ander Herrera.
The Red Devils went on to lose 3-1 as they chased an equaliser while Solskjaer has revealed what he told the Brazilian at half-time.
He said to stay on your feet and be sensible, while it was Fred's heavy touch that led to the slide tackle on Herrera and subsequent red card.
On the first-half incident, Solskjaer said: "Fred shouldn't put his head towards him. You don't do that. He's a bit lucky. It's either nothing or a red card."
When asked if he thought he should come off, he replied: "Yeah. But Fred has being playing really well. Played really well.
"We spoke about staying calm. Staying on your feet. The second yellow card is nowhere near a foul. Ander knows that. He definitely knows.
“I’m very pleased with performance apart from the fact they were more clinical.
“We need to be clinical in these type of games. Big games most of the time are decided by fine margins and this time they were against us.
“We know the destiny is in our own hands, we know that we play against a good team Leipzig, who were in the semi final last year, but we are developing into a better team as well."
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