The Steel has become the second New Zealand team to qualify for the ANZ Championship, but had to rely on an Australian side to help them get there.
The Queensland Firebirds beat the West Coast Fever 54-52 in Perth last night and joined the Steel in fourth place with 16 competition points.
But the combined Otago-Southland made progress courtesy of a superior goal percentage and will play the Thunderbirds in Adelaide on Monday.
Steel manager Gail McLauchlan mounted a nervous late night vigil which came to a happy ending shortly before midnight.
"We're really pleased.
''The heart was certainly going there for a wee while," she said.
Early in the third quarter the Brisbane-based side opened a eight-goal lead and seemed on track but the Fever fought back, winning the final quarter 16-13.
The television coverage included a live goal percentage tracker which added to the drama.
"We felt we were still in with a chance, but you never know with netball."
McLauchlan watched the coverage from Steel coach Robyn Broughton's home.
Broughton's phone was ringing off the hook with wellwishers from the moment the final whistle blew, but McLauchlan said the camp's thoughts were already turning to the Thunderbirds game.
The Adelaide-based side dismantled the Magic by 54-35 on Sunday and will be tough to beat on their home court.
In the other semifinal the Vixens will play the Magic in Melbourne this Sunday with the winner going directly to the final.
The loser of that contest will play the winner of the Steel-Thunderbirds match, with the winner moving on to the final.
Meanwhile, in the age group nationals in Auckland yesterday the Otago under-19 team opened its campaign with a 42-27 win over Wellington and backed up with a 41-27 win over Eastern South.
The Otago under-21 side split its matches, thrashing Counties Manukau 70-31, but losing to Auckland Waitakere 49-42.
• Silver Ferns coach Ruth Aitken said New Zealand's franchises need to concentrate on more than just their transtasman league teams.
She said Australia's depth is not the sole reason behind its second strong showing in as many years of the league: "Their depth is evident in this competition, but it's the structures and pathways they have through their state netball, which is very well organised, and their regional academies as well."
- Additional reporting by NZPA
