Goals from Yaya Toure, Samir Nasri, Edin Dzeko and Stevan Jovetic give Manuel Pellegrini's men a convincing win and move them to within a point of Liverpool
In a first half overshadowed by what appears to be a serious knee injury sustained by Jay Rodriguez, Yaya Toure put the home side in front from the penalty spot just three minutes in after Jose Fonte had felled Edin Dzeko, but Rickie Lambert brought the Saints level from 12 yards on 37 minutes.
But Samir Nasri slotted in a pass from an offside David Silva to put City back in front eight minutes later and Dzeko headed in Aleksandar Kolarov's cross immediately before half-time.
|VIEW FROM THE ETIHAD STADIUM
|By Tom Marshall-Bailey
If this was a test of Manchester City's standing in this title race, then they passed it with flying colours. This was a performance which featured all the characteristics of a title-winning side as Manuel Pellegrini's men combined flair and decisve attacking play with a resilience and maturity that helped to fend off a spirited Southampton side that deserved so much more than what, on paper at least, comes across as yet another team put to the sword at the Etihad.
When Jose Fonte upended Edin Dzeko and Yaya Toure subsequently stroked home from the spot, a nervy-looking Saints side looked there for the taking, but Mauricio Pochettino's side proved why they are the talk of the top flight this season with a gutsy response which yielded an equaliser through a penalty of their own, dispatched clinically by Rickie Lambert.
Jay Rodriguez's knee injury, however, threw the visitors out of their stride. City mercilessly capitalised. A two-goal salvo right on half-time was just the tonic for a visibly worried Pellegrini, as David Silva benefited from a kind offside decision to tee up Samir Nasri, before Aleksandar Kolarov's sumptuous cross was nodded home by Edin Dzeko.
The second half represented something of a procession for City, with Southampton unable to stir themselves for another comeback. Substitute Stevan Jovetic added some gloss to the scoreline late on as City proved just why they remain many critics' team to beat in this most thrilling of title races. City arrived here like they meant business and delivered a performance which said equally as much of their title aspirations. Chelsea and Liverpool, it's over to you.
The win keeps pressure on Premier League title rivals Chelsea and Liverpool, with Pellegrini taking his side to Anfield next week for a clash that could decide the destination of the trophy.
City made a barnstorming start, though they had Fonte's inexplicable trip on Dzeko to thank as Toure opened the scoring from the spot, sending Paulo Gazzaniga - playing in place of the injured Artur Boruc - the wrong way.
Nasri wasted a chance to double the advantage two minutes later, and the visitors eventually settled into the game.
Their momentum was checked when Rodriguez was forced off looking in distress after appearing to twist his knee in an awkward landing as England boss Roy Hodgson looked on concerned from the stands.
Despite that setback, Zabaleta then brought down Cork to give Lambert the chance to equalise from 12 yards - and the striker coolly maintained his 100 per cent record from the spot for the Saints.
Southampton had most of the play after their equaliser but were caught with a sucker-punch in the 45th minute as Nasri turned home from Silva's pass, though replays showed the Spaniard had been comfortably offside in the build-up.
Gazzaniga was arguably at fault for City's third, flapping at an Aleksandar Kolarov cross to gift Dzeko his 21st goal of the season.
The hosts controlled much of the second half and had several chances to extend their lead further in the period's opening 20 minutes.
Toure saw shouts for the game's third penalty waved away, Dzeko skewed horribly wide after seeing his initial effort saved and Gazzaniga displayed a better side of his game to keep Nasri out.
The fourth finally came late on as Jesus Navas gave Jovetic a tap-in as City took another step closer to the title, before Toure struck the post late on.
A fourth defeat in Southampton's last five away trips, meanwhile, hinders their late run for the top six.