'F****** disgrace, I have no words!' - Amad Diallo lashes out in X-rated outburst as Man Utd squad unrest boils over after Atletico Madrid defeat

Michael Carrick’s men travelled to the Metropolitano desperate to kickstart their stuttering campaign, but suffered an immediate blow. They conceded inside the opening 50 seconds, setting a grim tone for a miserable European night.

Despite the early shock, the visitors carved out several opportunities to equalise before a controversial red card for Leny Yoro derailed their momentum. Atletico capitalised on the numerical advantage, with Ademola Lookman eventually sealing the victory with 11 minutes left on the clock.

The contentious refereeing decisions infuriated the United camp. Taking to Snapchat in the aftermath, winger Amad did not hold back in his assessment of the officiating, posting: "F*****g disgrace I have no words".

Snapchat/@coloelpopo

The frustration extended far beyond the refereeing, with Lisandro Martinez delivering a blistering post-match interview. The Argentina defender pointed the finger directly at director of football Jason Wilcox over the club’s summer transfer business.

"Really poor [performance], really poor," a furious Martinez said. "I have to control myself a lot but sometimes it’s a reflection of the mirror of how is our club at the moment. We did a fantastic season last season and now we expect more from the top, from up, to be more players to compete because many, many teams bring many players as well. Atletico have an amazing team and they deserved to win today."

When pushed on whether United currently possess a squad capable of competing in the Champions League, the centre-back doubled down on his criticism of the boardroom.

He added: "I expect more, honestly. I expect more [investment]. Yeah, 100 per cent. I expect more from our technical director. We have to be honest and also as players we have to do more, but it is also important when you make a strong squad to be ready for this kind of night."

Martinez's scathing assessment will inevitably pile pressure on summer recruits Youri Tielemans, Andrey Santos, and Carlos Baleba, all of whom started in the Spanish capital. The overall mood within the camp has been heavily scrutinised lately, with captain Bruno Fernandes’ demeanour also drawing criticism.

Asked about Martinez's explosive remarks, Tielemans refused to be drawn into the debate. "I have no comment on that," the midfielder stated. "I don’t know."

Meanwhile, Santos issued an apology to the travelling supporters while insisting the dressing room remains firmly behind their manager. "I just want to say sorry to everyone that has travelled to Spain," Santos explained. "Of course, as I have said before, we want to win every single game. Now is time to work hard and come back with victories."

Backing Carrick, he added: "Of course, we believe in the manager, we believe in our staff, we believe in our players. Like I said before, we are in a bad moment, but we have to work to change this."

The fallout from this damaging European trip leaves Carrick facing an increasingly toxic atmosphere ahead of a pivotal weekend. United must quickly regroup before travelling to Elland Road to face bitter rivals Leeds United on Sunday.

Anything less than a victory in Yorkshire could spell disaster for the current coaching staff. With public signs of disunity creeping into the squad, Carrick must find a way to galvanise his players and salvage a season that is rapidly threatening to spiral out of control.