The Brazilian midfielder was given his marching orders in the second half after a second bookable offence for a challenge on former teammate Ander Herrera.
Fred was fortunate to even be on the pitch at all by that stage after escaping a certain red card when he headbutted PSG midfielder Leandro Paredes in the first-half.
The 27-year-old was sent off just seconds after United had fallen 2-1 behind through Marquinhos’ effort as Ole Gunnar Solskjaer paid the ultimate price for refusing to substitute Fred earlier.
Taking to social media after the match the Brazilian reflected on the defeat and sent a message of belief to the United fans.
“It wasn’t the best night, but we kept working for the best,” Fred wrote on his official Instagram page. “Always strong mind. We are United! #MUFC.”
Fred’s red card means he will miss the pivotal Group H trip to face RB Leipzig next week, with United knowing they will qualify for the knockout stages as long as they avoid defeat.
United will hope his absence does not cost them in Germany, but Solskjaer admits he should have taken Fred off at half-time on Wednesday night.
“The second yellow from Fred was not yellow,” Solskjaer told Viasport. “But maybe he should have had red before. I must maybe hold my hands up, I should probably have taken him off before.”