Down by 12 in the third quarter, the Adelaide side poured the pressure on the Southerners right through the final 15 minutes, as they had done with success against the Mystics the week before. But the Steel were able to keep their cool and score off their own centre passes in the dying minutes to salvage a much-needed victory.
It was the first win by a New Zealand side in this weeks Rivalry Round. But more crucially for the Steel, it was a win that captain Wendy Frew said puts the Southerners back on track for a semifinal spot after a rough start to the season.
After a jittery start to the match, played inside the ILT Velodrome, but quickly established a fast and fluid rhythm through the new midcourt trio of Frew, Natasha Chokljat and Liana Leota.
In defence, Leana de Bruin proved a perfect match for the Thunderbirds shooting weapon Carla Borrego, who was harried in her efforts to collect the big vertical bombs fired in by the Thunderbird midcourters.
The Steel maintained a three-goal advantage through most of the quarter, leading 14-11 at the first break.
Returning to the court with a new intensity rallied by captain Natalie von Bertouch, the Thunderbirds scored five in a row to create a two-goal lead. Goal attack Erin Bell and wing attack Emily Beatson tirelessly worked the ball through court.
But at the other end, Danekia Wipiiti and her shooting off-sider, Paula Griffin, were up for a challenge, and a trio of goals combined with a crucial intercept by de Bruin - swung the lead back the Southerners way.
Leota was essential to the Steels resurgence, dominating the feed on the edge of the circle and contesting every ball in a grand tussle with Thunderbirds wing defence Jo Sutton, who gave all she had to try to shut down the torrent of Steel ball.
Suddenly the Steel were up by nine running off court thrilled with a halftime lead of 29-21 and did not let their foot off the pedal as the third quarter began.
Disappointed with the penalty count accrued by her side, Thunderbirds coach Jane Woodlands-Thompson turned to a new goal defence in Georgia Beaton. The tighter defence was immediately effective, and the visitors pegged back a few.
But with de Bruin at her athletic best on the rebound and the intercept, the gap between the two sides stretched out to double figures 43-33 in the Steels favour at the end of the third spell.
Just when it looked like a foregone conclusion, the Thunderbirds returned to the court fresh and fired up. Young keeper Katie Shimmin was given her chance to make a difference, and when moved out to goal defence, Sharni Layton ramped up her game no end.
With the Adelaide sides vision through court clearer and sharper, they scored the first six goals of the quarter and closed the gap to four.
The experienced head of Sheryl Scanlan entered the game at wing defence, and the Steel regained composure to stop the Thunderbirds charge. Both Wipiiti and Griffin finished with imposing shooting percentages, with Griffins 21 from 23 one of the highlights of the match.