Match ends, Manchester City 6, Southampton 1.
Manchester City cruised to victory over a sorry Southampton side to return to the top of the Premier League.
City took just six minutes to open the scoring as Wesley Hoedt smashed an attempted clearance of Leroy Sane's cross into his own net, before Sergio Aguero doubled their lead by tapping in Raheem Sterling's cross.
David Silva slammed home their third from Sane's flick-on after 18 minutes but Danny Ings did pull one back from the spot after Ederson brought him down in the area.
Sterling then netted either side of the break to complete an impressive personal performance, while Sane added a late sixth to cap off a fine afternoon for Pep Guardiola's men.
Both of the England forward's goals were assisted by Aguero, as the Argentine first crossed for Sterling to stroke in, before a slide-rule pass enabled the 23-year-old to finish emphatically.
Sane's goal came deep into injury time, firing past McCarthy following a lightning counter-attack with Southampton legs tiring.
Guardiola's side have now won eight of their past nine matches across all competitions, although Ings' penalty was the first league goal they have conceded in six games.
Meanwhile, Saints are now seven Premier League games without a victory and lie 16th.
City may have taken the lead after just six minutes, as Hoedt's attempted clearance ended up in his own net, but Southampton had already been warned of their hosts' threat on several occasions.
In the opening moments, Aguero drove into the area only to be crowded out by three Saints defenders, before Sterling flashed a dangerous ball across the face of McCarthy's goal.
But Aguero was not to be denied for long, as he turned in Sterling's cross for his 150th Premier League goal, after the England forward and Bernardo Silva linked up classily.
McCarthy then had to be alert to save yet another Aguero effort, after the Argentine had been put through on goal by Bernardo Silva.
David Silva added his side's third in the 18th minute, his powerful volley from Sane's flick-on leaving McCarthy helpless.
The home side eased off after this early blitz, which saw them enjoy 81% of the possession in the opening 20 minutes, with a fifth straight league win over Southampton already in the bag.
Ings' penalty seemed to reignite the hosts' attacking threat, as City began to push again, in large through the excellent Sterling.
And it was the ex-Liverpool winger who netted their fourth, stroking in at the second attempt, after initially miss-controlling Aguero's pass.
After being heavily involved in all three of their opening goals, Sterling's effort, his fifth of the campaign, was richly deserved.
The England man was lively throughout, and although he could have done better with several half-chances, he illustrated his clinical side by powering in his second goal on 67 minutes.
Having earlier set up Aguero's tap-in, Sterling again turned provider late on, as it was from his pass that Sane netted City's sixth.
Sterling's brilliant display should not be a surprise, as he has now contributed to 25 goals in 19 Premier League appearances at the Etihad since the start of last season.
More to follow.
Match ends, Manchester City 6, Southampton 1.
Second Half ends, Manchester City 6, Southampton 1.
Attempt saved. Raheem Sterling (Manchester City) left footed shot from outside the box is saved in the centre of the goal. Assisted by Sergio Agüero.
Goal! Manchester City 6, Southampton 1. Leroy Sané (Manchester City) left footed shot from the centre of the box to the bottom left corner. Assisted by Raheem Sterling following a fast break.
Foul by Sergio Agüero (Manchester City).
Pierre-Emile Højbjerg (Southampton) wins a free kick in the defensive half.
Attempt blocked. Phil Foden (Manchester City) right footed shot from the centre of the box is blocked. Assisted by Raheem Sterling.
Corner, Southampton. Conceded by Vincent Kompany.
Attempt missed. Leroy Sané (Manchester City) left footed shot from outside the box is just a bit too high from a direct free kick.
Phil Foden (Manchester City) wins a free kick in the attacking half.
Foul by Wesley Hoedt (Southampton).
Attempt saved. Shane Long (Southampton) right footed shot from more than 35 yards is saved in the bottom right corner.
Attempt missed. Shane Long (Southampton) right footed shot from the centre of the box is close, but misses to the right. Assisted by Michael Obafemi with a cross.
Substitution, Southampton. Stuart Armstrong replaces Danny Ings.
Attempt missed. Sergio Agüero (Manchester City) right footed shot from outside the box is high and wide to the right. Assisted by Leroy Sané.
Delay over. They are ready to continue.
Delay in match Mario Lemina (Southampton) because of an injury.
Substitution, Manchester City. Fabian Delph replaces Fernandinho.
Offside, Manchester City. Sergio Agüero tries a through ball, but Leroy Sané is caught offside.
Attempt missed. Sergio Agüero (Manchester City) left footed shot from the centre of the box is high and wide to the left. Assisted by Phil Foden.
Substitution, Southampton. Mohamed Elyounoussi replaces Nathan Redmond.
Substitution, Southampton. Michael Obafemi replaces James Ward-Prowse.
Attempt missed. Danny Ings (Southampton) header from the centre of the box is too high. Assisted by James Ward-Prowse with a cross following a set piece situation.
Substitution, Manchester City. Phil Foden replaces David Silva.
Foul by Benjamin Mendy (Manchester City).
Nathan Redmond (Southampton) wins a free kick on the right wing.
Corner, Southampton. Conceded by Vincent Kompany.
Attempt blocked. Shane Long (Southampton) left footed shot from the right side of the box is blocked. Assisted by James Ward-Prowse.
Substitution, Manchester City. Vincent Kompany replaces John Stones.
Goal! Manchester City 5, Southampton 1. Raheem Sterling (Manchester City) right footed shot from a difficult angle on the right to the bottom left corner. Assisted by Sergio Agüero.
Attempt blocked. Bernardo Silva (Manchester City) left footed shot from the centre of the box is blocked. Assisted by Kyle Walker.
Attempt saved. Mario Lemina (Southampton) right footed shot from outside the box is saved in the top left corner. Assisted by Pierre-Emile Højbjerg.
Attempt missed. Mario Lemina (Southampton) right footed shot from outside the box is high and wide to the right.
Leroy Sané (Manchester City) hits the left post with a left footed shot from outside the box. Assisted by Sergio Agüero.
Foul by Kyle Walker (Manchester City).
Nathan Redmond (Southampton) wins a free kick in the defensive half.
Aymeric Laporte (Manchester City) wins a free kick in the defensive half.
Foul by Shane Long (Southampton).
Attempt missed. John Stones (Manchester City) header from the centre of the box is just a bit too high. Assisted by Benjamin Mendy following a corner.
Corner, Manchester City. Conceded by Mario Lemina.