Raheem Sterling scored the decisive goal in a hard-fought contest against a high-flying Saints side who had won 10 of their previous 11 outings and it was a welcome return to winning ways following a draw at home to struggling West Bromwich Albion.
The Baggies are next up for City, who travel to The Hawthorns on Tuesday 26 January in superb form, having won all ten matches since our previous meeting to propel ourselves up the Premier League table.
And for Guardiola, responding to that frustrating stalemate with the three points claimed at Southampton was a turning point in our season.
“It’s difficult to say,” said Guardiola when asked what has changed since the draw with West Brom.
“We won the next game at Southampton. That was one of the turning points.
“It was difficult and at that moment Southampton were in top form. We were able to beat them and then we started the process of playing better.
"We were far away from the top of the league, but then we started getting closer, training better, sleeping better.”
City travel to the West Midlands as the Premier League’s in form team and despite facing a West Brom side who have lost 12 of their 19 league games, Guardiola is taking nothing for granted.
The Spaniard is adamant his team will have to perform better than we did last month and is wary of the threat posed by new manager Sam Allardyce, who he predicts will be looking to take advantage of set-piece situations.
Guardiola says City must find a way to exploit the home side's weakness and has called on his players to impose themselves at The Hawthorns.
“We had chances to win that game but the way we played was not good in that time,” he added at his pre-match press conference.
“We have to play better.
“I know how good Sam Allardyce teams are on set-pieces. They will have worked this week on that to see how they can hurt us, but we have to discover the weak points they may have and impose our game.
“Today our training session was very good. I am optimistic to take a bus tomorrow to West Bromwich and do a good game.”
You can watch exclusive CityTV productions, including the recently released Shaun Wright-Phillips feature, with a CITY+ subscription.