Manchester City's Sergio Aguero celebrates scoring against Manchester United during their English Premier League soccer match at the Etihad Stadium in Manchester, northern England, Sept 22, 2013. [Photo/Agencies]

MANCHESTER, England - Manchester City delivered a ruthless attacking display to humble Manchester United 4-1 in the Premier League on Sunday, reasserting the team's title credentials and landing a major psychological blow on its fiercest rival.

Argentina striker Sergio Aguero led from the front for City in a one-sided derby, volleying home acrobatically in the 16th minute and adding his second amid a glut of three goals in a five-minute span either side of halftime.

Yaya Toure and Samir Nasri were the other scorers in a signature victory that City really needed to kick-start the Manuel Pellegrini era. United, however, will be reeling after being embarrassed at times by its neighbor just when the team appeared to have clicked under new manager David Moyes.

"After winning, the most important thing was how we won," said Pellegrini, adding: "No one believes that 4-1 is possible before the game."

Wayne Rooney curled a free kick into the top corner in the 87th minute - becoming the highest scorer in Manchester derbies with 11 goals - but that will be little consolation to the England striker or United, which fell five points behind early pacesetters Arsenal and Tottenham after five matches. The visitors sorely missed Robin van Persie, who was sidelined with a groin strain, and have now made the worst start to a league season in nine years.

"I've made them aware of what I think," said Moyes, whose side claimed just one point from matches against Liverpool, Chelsea and City in a tough run of early-season fixtures.

City climbed to third and has now scored seven goals in two matches, on the back of a 3-0 win over Viktoria Plzen in the Champions League on Tuesday. The influence of Pellegrini may finally be kicking in.

It equaled City's biggest home win in the derby since a mauling by the same score line at the Etihad Stadium in 2004. And when the influential Nasri volleyed in the fourth goal after 50 minutes, memories came flooding back of the 6-1 beating City handed its neighbor at Old Trafford in 2011.