In some ways this was a downgrade on many of Manchester City's recent performances. They conceded a goal, for one thing.
Yet there they are at the top of the Premier League table, with daylight - albeit a glimmer - between them and the chasing pack for the first time this season.
The debate around City has changed quickly over the first 11 games of their title defence. After the first few, plenty of City fans were concerned that their team was not quite at the same level of last season (this was despite winning every game bar an unfortunate draw at Wolves). As Pep Guardiola experimented with his tactics, many argued they had not quite 'clicked'.
Now, though, it is generally accepted that they are even better than the Centurions. Against Southampton they conceded their first league goal since September 1, Danny Ings converting a penalty that was won after the Saints had done what so few teams have in recent weeks; exploit the space between the City defenders and Ederson.
In the end it didn't matter; City scored six at the other end.
That brief defensive lapse, if you can call it that, has been the exception this season. City had conceded 10 shots on target in their first 10 league games, but six alone on Sunday.
Overall, though, they have conceded just four league goals all season, the best record in Europe's top five leagues.
Analysis published by Statsbomb ahead of City's win at Tottenham last Monday showed that while the Blues are allowing 6.44 shots per game, which is up from 6.37 last season, their expected goals conceded are down from 0.66 to 0.51. In short, City's opponents are just not getting clear-cut chances.
That is because they are usually too busy trying to defend their own goal. City have now scored 33 goals this season, which is the second most across Europe's big five. The goals are coming from everywhere; Sergio Aguero has seven, Raheem Sterling has six, Riyad Mahrez - who didn't even play on Sunday - has four. David Silva, Bernardo Silva and Leroy Sane have chipped in with three each.
A reminder: Kevin De Bruyne has barely featured this season.
Thanks to stats like that, the Etihad Stadium has become a fortress. Since losing to Chelsea in December 2016, City have lost just once at home in the Premier League. In that time they have scored 110 goals in 37 home league games, an average of 2.97 goals every time.
They are just as untouchable away from home; last season they picked up 50 of their 100 points on the road. This season they have already beaten Arsenal and Tottenham in London and claimed a goalless draw at Anfield, where it was expected that they would be out-gunned by Liverpool.
Guardiola spent the first weeks of the season warning his players not to get complacent. Clearly he has been successful. If they don't win the title this season it will not be because they have taken their foot off the pedal.
The chasing pack can still have their say, of course. For all of City's brilliance, the Premier League table has only allowed them to win a maximum of 33 points so far, and while they have racked up more than the rest, they have not been able to build up a huge lead. That is thanks to the merit of the chasing pack, who have been picking apart 'the other 14' top-flight clubs with ease.
Liverpool, City's principle challengers, have dropped their points against their title rivals, a suggestion that they still have some way to go to match the Blues' levels, but they are only two points behind.
Chelsea have lost a little of their early season shine in recent weeks but they are right up there, too, and even Tottenham, who have to contend with more negative stories than positive these days, are only five points back after what has been an impressive start to their campaign, results wise. A hungry-looking Arsenal are only a point behind their north London rivals, too.
If City are to win the league again they will simply have to keep this going, ensuring the gap to their rivals only grows as the season goes on. That is what they did last season and few would be surprised if they did so again. Another reminder: they have done all of this so far without De Bruyne, their most influential player.
And Guardiola is not satisfied yet, either: "The team shows me today that in some actions we are still not stable enough." He pin-pointed his side's problems with individual duels, "not defending passes between the lines", and sloppiness in possession.
“I like to have that feeling that we have won 6-1, that we are top of the table, we are satisfied again with the performance and how they fought until the last minute," he said, "but at the same time I have that feeling that we have improve in many many situations to be a stable team.”
Now they have opened a gap at the top of the table, that is a scary thought for their challengers.