A 77th-minute Cameron Munster field goal has fired Melbourne to a thrilling 29-28 win over South Sydney and within 80 minutes of another NRL grand final.
In a dramatic start to this year's final series, the Rabbitohs appeared to have clinched a preliminary final when Cameron Murray controversially stormed over with nine minutes to go.
But Munster set up a line break for Billy Slater and then nailed a 31-metre field goal to send a raucous crowd of 17,306 at AAMI Park into raptures.
The Rabbitohs now wait on the winner of Sunday's elimination final between Brisbane and St George Illawarra in next Saturday's semifinal.
The Storm had to come from behind five times in an absorbing contest, and also had to overcome a number of controversial refereeing decisions, to claim the win.
Scores were locked at 18-all midway through the second half when Curtis Scott was penalised for a second effort in a tackle that led to Robert Jennings crossing not long after.
A Cheyse Blair try levelled the game again, only for a sideline official to rule a Josh Addo-Carr forward pass that led to Murray's go-ahead four-pointer.
But Munster's late game heroics ensured the Storm remain on track to become the first team to defend their crowd in a unified competition since Brisbane in 1992-93.
Blair and Suliasi Vunivalu both finished with doubles, while Rabbitohs skipper Greg Inglis did his best to inspire his side to also nab a double.
"We were really happy with the way it ended up but we were probably lucky to win and they were unlucky to lose - it could have gone either way," Storm coach Craig Bellamy said.
"My main emotion is how proud I am of the team tonight."
Rabbitohs coach Anthony Seibold said his team were taught a lesson in finals football.
"They showed us in the key moments how to play finals footy," Seibold said.
"They put us under pressure with it. In some ways we did to them also - we scored five tries, made more metres than them.
"A couple of key moments, one on halftime and one towards the back end of the game ... we'll learn from that."
It was an explosive start to the final, with both sides, led by Sam Burgess and Felise Kaufusi, trading a number of stadium-shaking hits.
Poor defensive reads by the Rabbitohs, sandwiched by a crunching Kaufusi shot on Sam Burgess, ended in back-to-back Storm tries to Scott and Vunivalu and their first lead.
The visitors regained the advantage on a bizarre 37th-minute Inglis try, where Vunivalu gave up on the play as he appealed for an offload from the ground from Jennings.
But Storm halfback Brodie Croft - a last-minute inclusion for Jahrome Hughes - set up a crucial try with a 70-metre line-break and grubber for Vunivalu on the stroke of halftime.
It appeared the Storm were on their way when George Burgess was sin-binned for a professional foul upon resumption that resulted in a six-point lead.
However the Rabbitohs rebounded with back-to-back tries, only for the Storm to once again prove their big-game experience with another strong finish.
Rabbitohs halfback Adam Reynolds came off with a shoulder injury moments before the break but took the field upon resumption with what was described as a shoulder sprain.