Fernandes opened the scoring early on with a penalty but United found themselves 4-1 down at the break after goals from Heung-Min Son (2), Tanguy Ndombele and Harry Kane.
The Portugal international was substituted at half-time following Anthony Martial's dismissal but not before he raised his voice and "lashed out verbally".
According to The Mirror, could be heard shouting "We are supposed to be Manchester United!" after storming past matchday officials in the tunnel.
"You couldn't help but hear him," a source told the outlet.
"He was clearly in a rage after having a face like thunder when he raced down the tunnel.
"He laid into team-mates, accusing them of not upholding the proud name of Manchester United. He kept yelling, 'We are supposed to be Manchester United. This shouldn't be happening'."
While his colleagues took the brunt of his criticism, it's also reported he had a thing or two to say about the tactics deployed by manager Ole Gunnar Solskjaer.
The source continued: "It was clear that the manager also came under fire because he was going on about the wrong tactics.
"There were other raised voices, but his was the one which seemed to carry the main force."
Upon hearing news of him laying into his teammates, United fans are loving the passion the former Sporting CP midfielder is reported to have displayed.
Recently an old video of Fernandes losing the plot and kicking doors while at Sporting has been doing the rounds, suggesting he has got a hot head on occasion.
This week reports from Portugal claimed United are worried about the 'mental and physical wear' on Fernandes - fearing he is feeling the pressure from taking on such an important role within the team.
Featured Image Credit: PA
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