Manchester City, led by De Bruyne, showed the class immediately.
Already after five minutes, the Belgian superstar shot the ball into goal, played by Bernardo Silva.
United replicated after 22 minutes of play when Jadon Sancho beautifully snorted the equalizer into the far corner.
But the home team City would take the lead again, and again it was through De Bruyne.
Phil Foden then scored on his own but the shot was saved by David de Gea, but the ball bounced after a few seconds until De Bruyne who sent the ball over the goal line.
City would also continue to be the number bigger than the local rival this Sunday night.
The league leader had good control of the event and also made it 3-1 in the 68th minute.
And it was beautiful.
Kevin De Bruyne struck a 30 meter free kick home 27 minutes into the match. 4 - 0 for the home team.
In the end, City won 4-1 after Mahrez scored his second goal in the final stage.
They now lead the Premier League six points ahead of Liverpool, who have one match less played.
Both Anthony Elanga and Victor Lindelöf started at Manchester United.
Elanga had a difficult time on the field; the muddy surface was clearly affecting his technique.
Lindelöf played the whole match.