The Storm and South Sydney have delivered the best game of 2018 in a rollercoaster thriller that came down to an ugly Cameron Munster drop-goal.

A 77th-minute Munster kick has fired Melbourne to a thrilling 29-28 win that has them just 80 minutes away from another 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 stepped up to nail a 31-metre field goal to send a raucous crowd of 17,306 at AAMI Park into raptures.

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"That is one of the best games I have ever seen," Channel 9's Paul Vautin said.

"This has set an incredible benchmark for the rest of this final series."

The Rabbitohs now wait on the winner of Sunday's elimination final between Brisbane and St George Illawarra to keep their season alive next week.

Rabbitohs coach Anthony Seibold admitted his team has to get better.

"We were really good in patches," Seibold said.

"They showed us in the key moments how to play finals footy.

"They punished us for every error or every penalty that we gave. They put us under pressure with it.

"We'll learn from that. I'm really proud of the games effort. We came here to get a result.

"When you score 28 points you expect to win a game of footy. We didn't. that's why we need to be better."

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.

Storm coach Craig Bellamy said he was immensely proud of his team's fight.

"I am just so proud of our boys for hanging in there," he said.

"There were a couple of areas they really dominated us, but I couldn't be prouder of our effort.

"I thought we were really gutsy. To come back against a great side down six points with seven minutes to go, that was a great effort."

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. It was an explosive start to the qualifying final, with the hosts forcing an error in their first defensive set that almost ended in an opening try for Slater.

But the retiring fullback grounded a grubber on the dead-ball line, to which the Rabbitohs responded through an aerial raid for Dane Gagai to post first points. The ferocious collisions kept on coming with Sam Burgess jolting the ball free on an early play, while Inglis also had the wind knocked out of him by Vunivalu not long after.

Poor defensive reads by the Rabbitohs, sandwiched by a stadium-shaking Kaufusi shot on Sam Burgess, ended in back-to-back Storm tries to Scott and Vunivalu and their first lead.

The visitors regained the lead 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 — broke the game open with a 70-metre line-break and grubber for Vunivalu on the stroke of halftime.

And it appeared the Storm were on their way when George Burgess was sin-binned for a professional foul that resulted in Cameron Smith kicking the Storm to a six-point lead.

However the Rabbitohs rebounded with back-to-back tries, only for the Storm to once again prove their big-game quality 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.

Munster's field goal came after the Storm had trailed by six with just eight minutes remaining.

Captain Cameron Smith blew up at a referee decision which saw the Storm penalised for a controversial forward pass late in the game.

The Rabbitohs were able to take the lead three tackles later in the moment that many believed would decide the contest.

But there were a series of dramatic twists and turns left in the incredible contest.

The Storm struck back two sets later when Cheyse Blair scored his second try.

It left the game tied at 28-28 with four minutes left.

That's when Munster stood-up and slotted the most important kick of his NRL career.