After all their efforts to stop City from clinching the league in their 3-2 derby win last week, United offered a clear reminder of why they have not been close contenders for the title this year with an abject display, lacking in creativity.
And by winning the title with five matches remaining, we have equalled the English top-flight record (Manchester United in 1907-08 and 2000-01, and Everton in 1984-85 all won the top-flight title with five games to spare).
With the triumph, City have become a three-time Premier League winners - a feat they are achieving in seven seasons.
"If I had met him when I was 20 years old, I would have improved so much", the Belgium worldwide said.
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They won it in the last remaining seconds in 2012, and in the final match in 2014.
"Everything is to play for as I've said all along, we're in a relegation battle until we're safe".
It is their first league title since 2014 and their first under former Barcelona and Bayern Munich coach Pep Guardiola.
West Brom, to their credit, also kept probing forward but they lacked the class required to really open United up at the back.
Juan Mata believes Manchester United still have lots to play for this season after Man City's Premier League title win was confirmed in the most disappointing of circumstances on Sunday. You don't win titles with inconsistency. "Probably because I won eight championships, I was not in the moon with the victory against them because that doesn't make me feel super happy".
"The mental level, the day by day, everything must be consistent until the last day so one of the things we have to improve is consistency", he said. "In my opinion it affected for sure some of the people that were too happy just with that", he said. "We are frustrated ourselves with the performance and what we have to do is, from tomorrow, think about the next game and keep going, because we have very important weeks ahead".
This title won by the City would be the fifth in the history of the team.