The champions claimed all three points despite seeing France international Eliaquim Mangala dismissed with 15 minutes remaining at St Mary’s after the centre-back picked up a second yellow card for a foul on substitute Shane Long.
However, second-half goals by Yaya Toure, substitute Frank Lampard and left-back Gael Clichy allowed City to cut the gap on Chelsea at the top of the table to just six points after the Blues were held at Sunderland on Saturday.
Despite the first half ending goalless, the visitors would have been aggrieved not to have led at the break after in-form striker Sergio Aguero was brought down in the box by Jose Fonte just nine minutes in – only for referee Mike Jones to book the Argentinian for diving.
Both sides also had great chances to break the deadlock in an evenly contested opening 45 minutes, but firstly Saints frontman Graziano Pelle failed to beat City keeper Joe Hart from just six yards out.
And then when City forward Stevan Jovetic was played through on goal on the half-hour mark, Saints No. 1 Fraser Forster half kept the Montenegrin’s effort out, before centre-back Toby Alderweireld produced a last-gasp goal-line clearance to complete the job, and keep the scoreline level at half-time.
However, Saints head coach Ronald Koeman was forced to make an enforced switch at the break after Morgan Schneiderlin picked up a calf injury in the first period, with the Dutchman opting to move Alderweireld forward from his position at the heart of the Southampton back four into a holding midfield role.
City, though, were the team to score the crucial first goal after man-of-the-match Aguero pulled the ball back for the onrushing Toure to fire home through a crowd of players from the edge of the penalty area.
And while the powerful Ivorian’s 51st-minute opener may have taken a slight deflection off Alderweireld before flying past a helpless Forster, the home team could have no such complaints when City doubled their lead with only 10 minutes remaining on the south coast.
By that point of the match, Mangala had already received his marching orders for hauling down Long as the Republic of Ireland international ran through on goal, with spaces suddenly created for City’s forward-thinking players to exploit on the counterattack.
And that is exactly what happened late on as the hard-working Aguero found Lampard with time and space on the edge of the Saints box, before the veteran midfielder fired low into the corner of the net past a flat-footed Forster.
Meanwhile, Clichy added a slightly flattering third after 88 minutes when that man Aguero again unselfishly picked out his unmarked team-mate at the back post, with the Frenchman scoring his first-ever goal for the club with a simple finish.
JAMIE CARRAGHER’S VERDICT
There is no one better who we have seen over the last 10-20 years in terms of that position of coming on to a ball than Lampard.
I think he is only one Premier League goal now behind Thierry Henry – that is an unbelievable stat for a central midfield player, and City have to keep him.
I do not know what goes on with City and the link with New York [City FC], but he has to stay at the club.
Southampton: Forster (6), Clyne (7), Fonte (8), Alderweireld (8), Bertrand (6), Wanyama (7), Schneiderlin (7), Davisd (7), Tadic (5), Mane (6), Pelle (5)
Used subs: Yoshida (6), Long (7), Mayuka (6)
Manchester City: Hart (7), Zabaleta (8), Kompany (7), Mangala (6), Clichy (8), Navas (5), Toure (7), Fernandinho (8), Nasri (5), Jovetic (5), Aguero (9)
Used subs: Milner (7), Lampard (8), Demichelis (6)
Man of the Match: Sergio Aguero