Manchester City then struck back via Edin Dzeko before Samir Nasri finished an excellent volley to seal the win for them.
Joe Hart - 5.5
Hart had little to do the entire game but pick the ball out of his net twice - there was little he could do on both occasions.
Pablo Zabaleta - 6.5
Overlapped well and always got into dangerous positions to drag the play wide for his side.
Vincent Kompany - 6
The Manchester City captain had an excellent first half, never panicky even when being chased down by two opponents but was caught out of position in the second half when Southampton counter-attacked. He seemed not quite as fast, perhaps due to his calf injury from pre-season.
Joleon Lescott - 6
Like Kompany, Lescott was found wanting when Southampton counter-attacked and lacked the speed to chase down the ball. A generally solid performance let down by momentary lapses caused by poor positioning.
Gael Clichy - 6.5
Bombed forward to assist in the attack and his efforts came to fruit when his cross eventually led to Nasri's goal.
Yaya Toure - 6.5
Drove the game from midfield typically but found it hard to penetrate the Southampton midfield. Concentrated too much on attack though, and didn't track back quickly enough when Southampton broke on the counter.
Jack Rodwell - 6
A neat, disciplined debut for Manchester City's only signing so far. Rodwell kept it simple, facilitating the play forward with direct passes and not wasting possession. He was unfortunate to give the ball away (actually, it was the Southampton player who popped out of nowhere to intercept the pass) which led to Southampton's second goal, but had a fine game otherwise.
David Silva (Off 72') - 5
The usually-mercurial Spaniard had a poor game in terms of finishing. He missed the penalty, contrived to hit the bar with a clear shot under no pressure and had several chances to put his side ahead.
Samir Nasri - 8.5
The controversial Frenchman hardly have the ball away in an excellent outing. He grew more into the game as it went on and supplied a sublime through pass for Tevez to finish in the first half. It may be marginally offside, but it was nevertheless a brilliant pass. He then went on to seal the win for Manchester City with a fine volley inside the box.
Carlos Tevez (Off 86') - 8
A typical hardworking performance from the Argentine paid off with a coolly-taken opener to beat Davis at the near post. His hardworking performance from deeper in midfield to close down the ball was excellent and never stopped running for his side.
Sergio Aguero (Off 13') - N/A
The Argentine was unfortunately injured after a fair challenge from Clyne and had to be stretchered off. Cue groans of frustrations from Fantasy Football players who had him as captain.
Edin Dzeko (On 13') - 6
Despite getting onto the scoreboard, Dzeko had a rather poor game as a whole. His decision-making was poor in the final third - there were times where he could have passed to Tevez but chose to take the defender on instead and lost the ball too easily. Also, Nasri found him in the six yard box during the second half but he could not poke home from such close range.
Mario Balotelli (On 72') - 6.5
Balotelli made an immediate impact with the little time he had on the pitch by holding off two Southampton players in the box and laying off the ball for Dzeko to fire home from point blank range.
Aleksandar Kolarov (On 86') - N/A
Kelvin Davis - 5.5
Davis should have done better than to let Tevez beat him at his near post for the opening goal but had a decent game otherwise. He could do little about the goals conceded.
Nathan Clyne - 7
Clyne is one talent to look out for. He executed a perfectly timed sliding tackle from behind to dispossess Aguero (and unfortunately injure him in the process). Clyne, who was linked with Manchester United in the summer, showed his worth as he held his own on the flank be it against Nasri, Aguero or Dzeko.
Jose Fonte - 6.5
He was always quick to close down City players in the box and scrambled blocks to deny the Manchester City strikers on a few occasions.
Jos Hooiveld - 5
The defender had a tough time dealing with the Manchester City strikers and allowed the a little bit too much space in the box.
Daniel Fox - 5
He had a tough time up against Zabalet on the overlap and didn't clear his lines properly, having his header land to Nasri for the winning goal.
James Ward-Prowse (Off 65') - 6
The 17-year-old was given a baptism of fire having to make his league debut against the defending champions and held his own against the likes of Yaya Toure without showing nerves.
Morgan Schneiderlin - 6.5
He ran his heart out trying to close down Yaya Toure and Rodwell throughout the match but did an admiral job in deny the Ivorian time and space to take charge of the match.
Jay Rodriguez (Off 55') - 5
Expectations were high for Southampton's big signing on his league debut but he had a minimal impact on the game and was outmuscled and outran on the flanks.
Jason Puncheon (Off 85') - 5
He gave the ball away too easily on the few occasions his side managed to get the ball up front.
Guilherme Do Prado - 5.5
Performed the role of holding the ball up well, but had little else to contribute to his side.
Adam Lallana - 6.5
A stable performance from Lallana in midfield, grafting in defence when needed and linking up play to attack well. He also provided the assist for Davis' goal.
Rickie Lambert (On 55') - 7
The Championship golden boot winner last season took less than five minutes to make an impact in the Premier League, striking home with a first-time shot to equalise for his side.
Steven Davis (On 65') - 7
He took even lesser time than Lambert to make his mark, taking only three minutes to get onto the scoresheet in a similiar fashion to Lambert.
Billy Sharp (On 86') - N/A