The loss to City on Sunday afternoon means that, for the third time in less than 10 months, the Red Devils have been beaten by opponents reduced to 10 men before half-time.
Despite Phil Foden's dismissal, it was Erling Haaland's goal that made the difference during a derby where United posed little threat and as the final whistle blew they left the pitch with a whimper.
The result leaves United with just four points from four games, matching the club's worst start to a Premier League season as all eyes turn to Carrick who led the side back to the Champions League after taking over in January.
The former United midfielder is under immense pressure to turn the side around and fans have called for him to step down as troubles continue. Tribal Football spoke exclusively with Michael Owen, who now serves as Casino.org's ambassador, helping British players compare the best online casinos selected for UK players, about how ridiculous these attacks are on his former teammate.
Should Carrick be sacked?
What went wrong against Man City? Do you think Man Utd looked toothless?
"They could have created more. Yeah. I mean, I never get carried away when you hit the post from 30 yards. I mean, I don't really count that as a great chance. If you're creating chances, it should be inside the box, really. That'll give you a much, much better indication of what they're doing and how they're attacking.
"No, they did look quite blunt yesterday, but I don't think that. I don't think anybody can point the finger and say, "Right, that's a blunt attack." I mean, it was only a week or so ago that they were looking unbelievable against Ipswich.
"And I know Ipswich aren't the best team in the Premier League, but to tear apart a team like they did in the second half was like the Manchester United of old anyway. So, I don't think if you look at their goals return this season compared to the rest, I think it measures up quite favourably and I think I do think the attack is the least of their problems, even though it was blunt yesterday.
What are your thoughts on the Foden red card? Was it the right call?
"It's the right call, but it gives me no pleasure in saying it. Fernandez doesn't cover himself in glory, obviously. It's the dark arts of football. he probably deserved the yellow card.
"If they if we're going to play by the rules, then he probably deserved the yellow card for kicking Foden in the backside. He then leaned over and sort of got Foden, and Foden reacted. I mean, it's a split-second thing.
"We've all probably been there in life when you get fouled, you then get kicked again, then somebody stands over you in a menacing way. So listen I think you have got to give a red card in that situation, but it left a sour taste in the mouth."
Some supporters are calling for Carrick to be sacked online, what are your thoughts on this as his tactics come under question?
"Again, people saying four points out of four games he needs to be sacked is a crazy thought but yeah that's the question that's come in.
"No, I mean I was doing the game on TV with Joe Hart and and (Dimitar) Berbatov and as soon as the red card was flashed I said this might not help Man United, I think I think they are and have been a counterattacking team for some time.
"That's when they're at their best and all of a sudden, when Manchester City go down to 10 men and it means Man United are going to have more of the ball, I don't think that necessarily suited them in that game.
"We've seen actually a big swing this season so far in a lot of teams that don't have the majority of the ball winning games. So yeah, it's one of those strange things when they go down to 10 men.
"I didn't think it necessarily had an advantage. In terms of Michael Carrick and his position, I think it's ridiculous to say that his job is under threat.
"He's done an unbelievable job so far at the club and no I think it's way, way too early to be talking about that."
Carrick was handed the permanent job after presiding over 12 victories in 17 games when in temporary charge following Amorim's dismissal. Despite his impressive record, questions will now be raised over his role at the club, especially if results do not start to go their way.
Owen worried for the state of refereeing
One of the biggest controversies from the derby was Haaland's goal, which was given despite calls for an offside. The refereeing body Pro Ref has admitted an error after VAR awarded City the goal despite it being initially deemed offside on the pitch by referee Michael Oliver.
Owen admitted that if such a decision can be looked at for several minutes and still be wrong, it makes him worried for the state of officiating in the Premier League.
Many have criticised Haaland’s goal for maybe being offside? Do you think that’s right or do you think it’s a bit desperate from fans?
"This is simply not up for debate. The PGMOL have come out and already said that it was a mistake. We all could see it was a mistake.
"You can read the rules and you know it's a mistake and sometimes you have sympathy. Sometimes there's lots going on and they are under pressure to make these decisions quickly and all the rest of it.
"So sometimes you do have sympathy, but in this case they had ample time. In fact, they took three and a half minutes or something. It was enough time to and it's not like there was three, four, five things that they had to look at.
"I mean, it was a pretty simple, straightforward decision. So, I just do not for the life of me understand and the worrying thing is that on these games you tend to put the best officials and if the best officials can make such a big mistake like that, then it does make you worry."
What has happened to United's defense?
The 199th Manchester derby will be remembered for two controversial refereeing decisions on Foden and Haaland, but the real question United fans will be asking is why their defense has collapsed this season.
Owen suggests the problem is that United need a refresh at the back, something the club may be investing in when the winter transfer window rolls around.
United have conceded 7 goals in 4 games, what’s gone wrong at the back?
"Yeah, I suppose so. I mean, small sample size so far, but they haven't really done much with their defence for a long time now. If you go back five years, it's virtually the same defence.
"Obviously Shaw wasn't playing yesterday, but it's a very, very similar defense than it was years and years and years ago, and all the rest of the team has evolved and changed.
"And sometimes consistency is a good thing. So, it's not like it's a bad thing, but yeah, it's probably the next area that Manchester United will be looking at to strengthen."