Over the last few weeks Saints have been quietly getting on with the job of putting a run together that has seen them move up the table into the play off places, this was another big step in showing their doubters they can be genuine promotion contenders.
There were a few raised eyebrows at 11.30 am when the team news came out, Ryan Manning was back in the squad but not in the team, with James Bree preferred at left back and also restored to the starting line up were Stuart Armstrong, Taylor Harwood-Bellis, Charly Alcatraz & Kamaldeen Sulemana.
This suggested that Russell Martin was going for the attacking option, but was also shoring up the back line a little by including the more defensive minded Bree.
This paid early dividends Adam Armstrong put in a superb cross from the left touchline that was met perfectly by Taylor Harwood-Bellis to head home, ironically TV replays showed that the Saints man was slightly offside, but with no VAR there was no hanging around to find out and the linesman's flag had stayed down.
So 1-0 up after only 9 minutes was a great start and it got better on 22 minutes when Sulemana was the provider and again a perfect low cross saw Charly Alcaraz slot home from close range.
Now it was all Southampton FC and although they were not the greatest team that the World will ever see, they were pushing Wayne Rooney's Blues onto the back foot and a third goal looked likely.
Adam Armstrong raced through only to fire wide with just the keeper to beat and Saints were in control.
But there was one worrying moment, Burke for the visitors got to the ball first and was felled by Gavin Bazunu, luckily for Saints again there was no VAR, otherwise the half time scoreline might well have been 1-1 and not 2-0 to the home side.
The second half started with Saints in control, but just before the hour mark came the obligatory lack of concentration and a sloppy goal conceded, Birmingham had only one tactic and that was to hump it up field, on came Jay Stansfield to join Southampton born Lukas Jutkiewicz up front.
Within seconds of his arrival came another hoofed ball up field and when it fell to Kyle Walker Peters, rather than clear it he attempted to control it and Stansfield pounced and fired home a goal that had not looked likely, in fairness to KWP this was a rare error from the full back.
Birmingham suddenly saw the light and for a period pushed forward, but Saints got their grip back and used possession football as a way of calming the situation.
But the crowd were understandably edgy, but although their nerves were jangling those on the pitch kept calm and they took control again, the game was made safe when yet another great cross into the box, this time from Ryan Fraser was headed down by Sam Edozie and Adam Armstrong pounced to fire home from the edge of the six yard box. on 86 minutes.
So overall this was not quite the perfect performance from Saints, but it was another good one, 4 weeks ago they were under fire after 4 straight defeats, but since then we have played 6 games of which we have won 4 and drawn the other 2 and in doing so pushed ourselves up into 4th place.
But in those 6 games we have sorted out our defensive woes, indeed it could be said that this has been the case over the last two games of that 4 game losing streak, in the last 8 games we have conceded just 9 goals, yes perhaps it needs to be a little better, but we are getting there.
The early issue of this run was scoring goals, now having built a foundation from the back we are finding our scoring boots, in this 6 game unbeaten run its just 6 goals conceded and 12 scored, these are very pleasing facts.
Russell Martin has used his squad well and this is why we are now flourishing, compare our substitutions with Birmingham's, we brought on quality in Ryan Fraser, rising stars such as Shea Charles and Same Edozie and the experience of Joe Aribo, Birmingham had 33 year old veteran Marc Roberts, 31 year old's Scott Hogan & Gary Gardner, free transfer Koji Miyoshi and the goal scorer 20 year old loanee Jay Stansfield.
This was a similar situation at Hull & Preston, our depth of squad will see us home in the second half of games.
This was very much a team performance, the balance was perfect both in the starting line up and also the substitutions made, in the first half it was attacking mode and also covering the defensive limitations offered by Sulemana by playing James Bree behind him, a defender rather than wing back.
In the second half we made key changes and brought on players who were not so free spirited as either Charly Alcatraz or Sulemana who could help see the game out.
It was hard to name a man of the match, the sponsors named Jan Bednarek, I could not see that myself, although the Pole had a good game, perhaps the fact I barely noticed him suggests that he had a good game and he is forming a partnership with Taylor Harwood-Bellis that at the moment looks like being the one that will see us through the season.
For me our best players was Adam Armstrong, not only did he put in the perfect hanging cross for THB's headed goal, but he worked his socks off and made a contribution defensively, all capped off by the late goal that meant we didn't have to worry in the final stages.
He has been a key player this season, his 8 goals see him 2nd highest scorer in the Championship only 1 behind Sunderland's Jack Clarke, he is the 22nd highest provider of assists in the division, and 2nd in the Saints squad, only Sulemana with 3 has more than his 2.
His overall work rate perhaps goes unseen by some, but it is phenomenal, so for me he edges man of the match and is an early contender for player of the season.
So a pleasing weekend and now we have to keep building on the good work of the last month, the first job is to make sure that we are putting daylight between us and 7th place and so are nailed on for a play off spot, after that we have to keep on hunting down the top 2, Leicester look strong enough to last the course, but Ipswich may struggle as winter takes it's toll on their squad.