Both teams struggled to create clear-cut chances in the second half, with Caglar Soyuncu's powerful header from a corner in the 66th minute proving to be the decisive goal.
The defeat means that Manchester City have now recorded their third Premier League title in four years, and here's what the United boss had to say after the game:
On how the game panned out:
"We started off a bit slow, as you might expect, because they have not had any time to prepare for the game. Maybe there were a couple of nerves but, after they scored, we had nothing to lose and I thought we played some very good stuff and I was pleased with it. We did not have too much time to prepare and we went into half-time quite pleased but then didn't quite get out of the traps."
"They got a goal from a corner that was never a corner. It was a throw-in. So that is very disappointing for us. I thought we played well and could have got a point near the end. Maybe we should have created more in the second half but I am happy."
On United's youngsters:
"The young kid Amad did really well, Mason [Greenwood] again he looked a seasoned professional out there. He’s only 19 but the way he has played tonight it was very, very good. He was fantastic leading the line next to an 18-year-old and a 19-year-old, he looks like a 29-year-old. I'm very pleased with him. Anthony [Elanga] was full of enthusiasm and positivity, with runs in behind and good defensive work."
"Mason scored a very good goal, it was agreat pass by Juan [Mata], a fantastic run, good timing. You can see Amad all day with his timing, his deceiving runs. I thought he played really well, and Mason scored, as he always does.”
On the congested fixtures:
"It can’t be like this again. You can’t play Thursday, Sunday, Tuesday, Thursday - it is impossible. So that’s the reason why we had to make these changes because it is unheard of. I say it again, if this game was tomorrow, no problem and if we have another game on Saturday."
"If you have two days in between, there is no problem but this is impossible for the players to perform at this level Thursday night, Sunday, Tuesday, Thursday. It is impossible.”
On challenging Manchester City:
"That's what we want, we want to push them, we want to go one step further. I don't think it's a shame when you look at their team, you don't have to be embarrassed. They've had a great season - you've got to be big enough to say congratulations and they're worthy champions - they have played really well this year."
"We pushed them until the last 10-12 days and that's quite an achievement after losing three of the first six games. The way we had to start, there's so many circumstances that made this a difficult season. You can't win the league in the first eight but can you lose the chance to win the league in the first eight and, when you lose half of your first six games, it's going to be difficult."
What's next for United?