Despite their good start upon their return to the Premiership, Birmingham offered nothing to make Saints self-belief unwarranted.
Antii Niemi was replaced by Paul Jones through injury, while Chris Marsden was suspended allowing the Svensson/Oakley/Delap trio the rare chance to appear in the same side.
The game began sluggishly as Birmingham did well to prevent Saints getting off to their trademark bright attacking start. Indeed, it was Birmingham who had the first chance with an unmarked Clinton Morrison left free from a free kick. Fortunately Morrsion could only put the ball wide.
At the other end, James Beattie made a good run before cutting the ball back for Anders Svensson whose shot was saved by Vaeson from fifteen yards.
A minute later, Wayne Bridge was inches short of getting onto the end of a Rory Delap cross. Delap put in another tenacious performance yesterday, and is steadily showing his worth to the club. Delap had a shot himself shrotly afterwards, but this was blocked.
The game rarely moved up form it's steady, patient pace in the opening twenty five minutes as Saints looked for ways to break through the visitors. Once again Morrison was found in plenty of space, although his tame shot was saved comfortably by Jones.
Saints reacted to this by almost grabbing the opener. Michael Svensson almost headed Saints into the lead at th mear post from a Fabrice Fernandes cross after a corner.
Saints began putting pressure on the Birmingham back line after putting together some good passing moves in midfield. Anders Svensson's through ball broke through the defence but was just inches ahead of James Beattie. Beattie then fired in a quick shot from twenty five yards as the opposition defence ran to close him down. The effort didn't trouble the Birmingham goal.
A one-two between Ormerod and Beattie forced Vaeson to save from Ormerod at a narrow angle.
With the pressure mounting Damian Johnson had to clear the ball off the Birmingham line after tow Saints corners. Matt Oakley then put his shot over the bar.
Then it was Anders Svensson's with a great chance to put Saints ahead. Svensson got way from his marker but only managed to put his curling shot past Vaeson wide of the post.
By the end of the first half the game was all Southampton. Birmingham's defensive approach, with the hope of catching Saints on the break, wasn't paying off and then had retreated into trying to soak up pressure from the home side.
Birmingham started the second half more brightly than they had finished the first, with Brian Hughes getting a well wide shot in on the Saints goal.
Rory Delap countered with a great run to earn the home team a corner. Matt Oakley's shot from Svensson's corner went over from twenty yards out.
Saints next chance as from centre half, Michael Svensson, who got on the end of Anders Svensson's through ball. Vaeson was relied upon to prevent it gong in.
Saints had regained their dominance within ten minutes of the restart. The Birmingham defence had to clear Beattie's header after Vaeson had failed to collect the ball from a Saints cross.
It took a set piece to finally end the deadlock. Referee Winter adjudged that Darren Purse had handles the ball in the area from a Wayne Bridge cross. While many thought the ball went to hand, James Beattie stepped up to convert his 6th penalty of the season. Beattie has had plenty of chance to become the Saints established penalty taker this season, and look s as though he has taken on Matt Le Tissier's mantle.
A goal down, Birmingham had no option but to move forward. Anders Svensson made an overhead kick clearance as Paul Jones failed to collect a cross. As good as Jones is, there's no question that many would prefer the quick return of Niemi.
Birmingham then had a penalty claim of their own as Tebily's shot deflected clear. Referee Winter ruled that on this occasion the ball had struck the hand and play continued. This was much to the annoyance of Morrison who received a booking for his protests.
Saints continued to dictate much of the play, as Anders Svensson, put clear past a quickly chasing Birmingham defence, failed to trouble Vaeson
With only a one goal lead, Saints weren't looking entirely secure. Birmingham were getting plenty of corners, none of which were capitalised upon.
Vaeson's clearance at the other end, almost rebounded back into his own net as it hit off of Beattie.
Birmingham made a double substitution to try and change things round, but it was Jo Tessem, Saints sub who would have a greater impact.
Only on a couple of minutes, Tessem's cross from the right was flicked on at the near post by Anders Svensson. James Beattie was waiting at the back post, to put the ball past Vaeson for his eleventh goal of the season.
With the second goal, the game was beyond Birmingham and Saints continued to dominate the game as they had done for practically the whole match. Paul Telfer came on for Fabrice Fernandes just to add some steel in the closing minutes, but Birmingham never looked like working their way back into contention.
After a good, solid home win Saints found themselves in seventh spot in the table and unbeaten at St. Mary's this season.