Two goals from Sergio Aguero and strikes from Yaya Toure and Nasri did the damage for Manuel Pellegrini's men at the Etihad Stadium, though Wayne Rooney grabbed a late consolation.
The result was a far cry from last year's corresponding fixture, which saw Robin van Persie netting a late free kick winner for United and Nasri castigated by his own fans for seemingly ducking out of the wall.
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“Last year I was involved in the third goal in a bad way, so this was a little revenge. I just want to share this moment with our fans.
“Last year was a little bit sad because we were losing 2-0 and came back, but in the last minute Robin scored that free kick.
“This year it was not the same scenario, and we are very happy.
“It was a big statement. We have sent a message to our rivals that this year we can be a force. To win like that is always special.
“We showed what good players we have in our team because we put in a very good performance.”
City's victory moves them up to third in the Premier League behind Totteham and Arsenal, and Nasri believes his side are well poised this early in the season.
“It was important to win this game, for ourselves as well as for the fans, because Arsenal won as well, and moved to 12 points,” he added.
“We won our first game in Champions League, which gave us confidence and we have trained really well. When you arrive at the game you have confidence, because you know what you can do.
“It was exactly that kind of game. We played our own kind of game, and won 4-1.
“At Stoke it was difficult because we came back from being with our national teams for ten days, and had players who had travelled all over the world, so when you come back you are not really fresh.
“But the win in Plzen made us really confident, and we did exactly what we had prepared for in the week.”