It battled to a 1-1 draw at Kiwitea Street on Saturday in what coach Paul O’Reilly described as a "smashing effort".
A 72nd-minute goal from youngster Ben Wade did the trick, capitalising on a mistake from Auckland goalkeeper Enaut Zubikarai.
After his clearance went awry, Zubikarai was caught out of position and Wade found the net from range, with a superb left-foot finish.
It was the key moment, after the vising side had gone behind to a Micah Lea’alafa goal in the 47th minute.
However, it was the defensive effort that caught the eye.In its eight games against the other sides, Auckland City averages 3.38 goals per game.
Southern has held it to three goals in two games.
O’Reilly said his side set up defensively and played deep.
That enabled it to limit Auckland’s chances and create some for itself on the counterattack.
While Auckland dominated possession, the Southern defence proved tough to break down and its only real lapse came in the conceded goal.
O’Reilly said the team was thrilled with that effort, although felt it could have been even better.
"To be honest, we’re even disappointed with the goal we conceded yesterday, because we had defended so, so well," he said.
"It was just a little switch-off that they got us on.
"But we’re delighted to keep them limited in terms of their chances on goal.
"It certainly gives us belief going forward.
"Last week we probably had eight or nine players that felt they underperformed last week, whereas yesterday we had good performances all over the place.
"So it was the performance more than the result.
"The performance, the work rate, the attitude was there. It was a smashing effort, really pleased."
The match ended a tough run for Southern, in which it has played the league’s top three teams in consecutive games.
From those games it emerged with draws against both Team Wellington and Auckland City.
Having also managed a 2-2 draw in round one against Auckland City, it was pleased to have secured three points against the league’s two top teams.
O’Reilly said it was important that side now pushed on and continued to pick up points in the coming weeks.
Southern United has signed 24-year-old Alex Ridsdale.
A former New Zealand under-17 representative, he comes to the side from Tasman United.
O’Reilly said Ridsdale, an attacking midfielder, would bolster the side in giving it another threat.
