Three second-half goals from Yaya Toure, Frank Lampard – plus a first-ever goal for Gael Clichy, completed City’s best performance of the season.
It was the Blues at their very best and the biggest statement yet that the champions won’t give up their crown without a fight.
Southampton ‘s home record going into this game could only be bettered by Premier League leaders Chelsea with five wins from six and just one goal conceded.
Considering the talent drain the Saints had suffered over the summer, their form this campaign is a credit to both new boss Ronald Koeman and the players he has brought to the club.
City’s early season slips, however, made this a must-win game with the chance to make ground on Chelsea and leap-frog into second place giving Manuel Pellegrini’s men a double incentive.
With Yaya Toure and Fernandinho both recalled after serving their midweek suspension, the game began in bright south-coast sunshine as the champions looked for their first victory at St Mary’s since 2003.
City started brightly and but for a truly baffling decision by referee Jones, would have been given the chance to take the lead from the penalty spot when Sergio Aguero was scythed down in the box.
Not only did he deem it not a foul, he booked the Blues’ talisman for diving – even the majority of the sell-out home crowd were scratching their heads at what was a clear foul.
Though City were largely dominant, there was a lucky escape on 21 minutes when a deep cross caused confusion and Joe Hart was forced to make three saves in a matter of a few seconds with Vincent Kompany also making a superb saving tackle as the hosts tried to force the ball home.
Ten minutes later and it was Saints who managed to scramble the ball off the line as a smart counter-attack by City saw Samir Nasri play in Stevan Jovetic whose shot was cleared off the line with Fraser Forster beaten.
That was the last clear opportunity of an entertaining first period that City had largely bossed without reward.
Saints came out with their tails up and two fierce long range efforts from Toby Alderweireld and Dusan Tadic saw Hart scrambling across his goal, but the Blues hit back immediately and finally broke the deadlock on 50 minutes.
Aguero received the ball in the box and cut inside a couple of challenges before teeing up Yaya Toure from the edge of the box and the Ivorian cracked home a low deflected drive that gave Forster no chance.
City went looking for a killer second with a James Milner corner causing chaos in the Saints box – but the ball just evaded the boot of Eliaquim Mangala and Fernandinho – and on 72 minutes Jesus Navas won possession outside the box and sent in a low drive that was inches wide.
Just three minutes later, though, the complexion of the game changed when Mangala was adjudged to have fouled Tadic on the edge of the box and was booked as a result – his second yellow of the afternoon meaning an early bath for the Frenchman.
It was a marginal decision to say the least and one perhaps won by the baying home crowd. Thankfully the Blues had a ready-made replacement in Martin Demichelis as they sought to close out the final quarter of an hour.
And they did so in style, with Milner breaking forward, biding his time before playing the ball to Frank Lampard who drilled home a beauty past Forster from the edge of the box – as he has done so many times during his magnificent career – to seal the points.
Aguero should have made it three five minutes from time but he was denied in a one-on-one with Forster – a collector’s item!
The best was saved to last, however, as a sweeping move saw Demichelis play the ball to Aguero whose exquisite pass found Clichy who bagged his first ever City goal. Fantastic stuff.
A classy display by the champions who are warming up nicely and have proved that the title race is only just beginning…
