Manchester City stepped up the pressure on their Premier League title rivals with a 4-1 victory over Southampton at the Etihad Stadium on Saturday.

Scheduled to play before Chelsea and Liverpool in this weekend's round of fixtures, Manuel Pellegrini's side took full advantage with Yaya Toure's third minute penalty setting them on course for victory and Stevan Jovetic wrapping up the win in nine minutes from time.

In between, they had been forced to overcome the shock of conceding a 37th minute equaliser to Rickie Lambert's penalty before regaining control with two goals in first half added-time from Samir Nasri and Edin Dzeko -- although City clearly benefited from an incorrect offside decision in the build-up to Nasri's goal.

For Southampton, defeat came with the added cost of a serious-looking knee injury to Jay Rodriguez that could rule the forward out of England's World Cup plans.

City have found Southampton to be testing opponents since Mauricio Pochettino was installed as manager of the south coast club and Manuel Pellegrini's side were entitled to regard this as a challenging fixture at a time of the season when they can ill-afford to slip up.

Home nerves were quickly eased when City were gifted the perfect start following a costly misjudgement by Jose Fonte that led to Toure's opening goal.

The opportunity was created by an incisive break, started deep in the home half by Toure and continued by David Silva who released Dzeko wide on the left. The striker advanced into the penalty area and cut and wrong-footed Fonte before being tripped by the defender's trailing leg.

Toure converted the penalty with ease, sending Paulo Gazzaniga -- the Saints keeper drafted into the side in place of Artur Boruc who injured his back in training -- the wrong way.

Having seen his team handed the platform of an early goal, Pellegrini might reasonably have expected to see City assert their authority.

But it was Southampton who responded more positively, enjoying extended periods of possession without really troubling England goalkeeper Joe Hart.

The game lost momentum midway through the first period when Rodriguez was stretchered off after landing awkwardly on his right leg as he attempted to control a high ball in the 26th minute.

Nine minutes later Dzeko missed a glaring opportunity to double his side's lead when he headed Nasri's free-kick against the bar from just four yards out.

Southampton's resilience had already been shown to be impressive and they drew level in a manner that matched City's opener.

Mirroring Dzeko's earlier move, Saints' Jack Cork cut in from the left before being sent tumbling by an unconvincing challenge by Pablo Zabaleta and Lambert capitalised by sending a firmly struck penalty beyond Hart's dive.

City had been jolted from their comfort zone and they may have faced a more difficult second period had they not scored twice in stoppage time.

Saints, though, had every right to feel aggrieved that City's second goal was allowed to stand with Silva clearly in an offside position when he received Dzeko's flicked pass before squaring for Nasri to roll home.

Yet they could only blame themselves for the poor marking that allowed Dzeko to head home unmarked from Aleksandar Kolarov's left wing cross seconds before the break.

City played with a more noticeable swagger after the interval and Dzeko should have added a fourth goal when he shot over just before the hour.

They had to wait until the 81st mintute before the final goal came when Jovetic turned home Jesus Navas's cross within a minute of coming off the bench.