AFP/London

Both managers had claimed in the build-up to the game that their team was the biggest in the city, but it was Manuel Pellegrini’s City who prevailed after Chris Smalling’s brainless first-half dismissal handed them control.

The United centre-back saw two yellow cards after trying to block a clearance by Joe Hart and then fouling James Milner, and after seeing three penalty appeals waved away, City eventually took the spoils thanks to Aguero.

The Argentine’s 63rd-minute strike ended a run of three winless games for City, who climbed back to within six points of leaders Chelsea ahead of Wednesday’s crucial Champions League meeting with CSKA Moscow.

Victory gave third-place City a fourth consecutive league win over their neighbours for the first time since 1970, and left Louis van Gaal’s United seven points behind the champions in ninth place.

To compound matters, United lost centre-back Marcos Rojo to a shoulder injury in the second half, but Van Gaal will have drawn encouragement from his side’s dogged showing on a ground where they lost 4-1 last season.

City were missing the injured David Silva and received a late blow when Aleksandar Kolarov was forced to withdraw from the starting XI after injuring himself in the warm-up, with Gael Clichy coming in.

The hosts were first to threaten, David de Gea parrying from Aguero, but United, with Wayne Rooney operating in a deep-lying number 10 role on his return from a three-game ban, began to probe.

Angel di Maria twice forced City back with crosses from wide on the left, but from the first Adnan Januzaj sliced off target and from the second Robin van Persie headed wide.

Beneath autumnal sunshine, it was a bitty start to the game, but mid-way through the first half the home team came to life and De Gea was obliged to ride to United’s rescue three times in quick succession.

After gathering a shot from Aguero, he had to tip a close-range effort by Jesus Navas over the bar and then showed tremendous bravery to save at Aguero’s feet as the Argentine attacked Fernando’s left-wing cross.

United weathered the storm, but they gifted City the momentum when Smalling was needlessly sent off in the 39th minute.

Having received a first booking for standing in front of Hart as the City goalkeeper looked to launch a clearance, he foolishly flew in on Milner, leaving referee Michael Oliver with no option but to dismiss him.

United’s ensuing reorganisation saw Januzaj concede his place to Michael Carrick, who made his first appearance of the season. It could have been even worse for United, but Oliver twice rejected strong penalty appeals from City—the first when Marouane Fellaini kicked the back of Aguero’s foot, the second when Rojo clattered Yaya Toure from behind as the Ivorian sought to bring down a high ball.

United were forced into another defensive reshuffle early in the second period when Rojo had to be stretchered off and given oxygen after injuring his shoulder in a sliding challenge. Paddy McNair took his place.

Aguero saw another penalty shout ignored after being clipped by Carrick, but City’s persistence paid off in the 63rd minute. Toure found Clichy with a beautifully weighted pass down the inside-left channel and the Frenchman crossed for Aguero to sweep home left-footed from 10 yards.

With the home fans scenting blood, City manager Pellegrini sent on Samir Nasri and Edin Dzeko for the final 20 minutes. Navas hit the post after a scuttling run but United finished the game strongly, with Hart blocking from Van Persie and getting down well to save a low right-foot shot by Di Maria after a bulldozing Rooney run.

Tottenham scored twice in the last 10 minutes to beat Aston Villa 2-1 in the day’s other match, handing the visitors a sixth straight defeat in the league, their worst run for 47 years.