Penrith had to summon halfback Nathan Cleary to etch his name into NRL grand final folklore late amid the greatest recorded grand final comeback of all time while also denying Ezra Mam from directing Brisbane to a first title in 17 years.

The defending premiers fought back from 16 points down to convert three successive tries to hit the front just in time with a thrilling 26-24 victory to secure the Panthers a third premiership in a row, a feat that has not been achieved in the past 40 years.

But Mam, the young Broncos playmaker, more than just threatened to slice the season decider wide open early in the second half, which yielded three barnstorming tries, all in what appeared to be a blink of an eye.

The Kuku Yalanji and Torres Strait Islander man was set to lean forward and bow his head to accept the Clive Churchill Medal from Aboriginal legend Cliff Lyons until he didn't.

It would have been a fairytale for Mam after the second-year player was participating in a Torres Strait Island dance troupe just three years ago in the midst of the pandemic grand final that had him playing it up in front of half the vacant seats.

That year looked to have an odd piece of symmetry about it at one stage on Sunday night after the last time this resilient Penrith unit had lost on the grandest stage of all was to Melbourne Storm.

But the only kind of coincidence that was shared was the Panthers coming back to the very end.

Again it was Cleary, with his deft hand in two return tries that cut the margin back in a rush before crossing for Penrith's matchwinner in the 76th minute sealed the ownership of the award for the grand final's best player right out of Mam's grasp.

But in a class act of sportsmanship, Cleary made sure he went out of his way during a modest acceptance speech to single out Mam for a performance beyond disbelief that also woke both sides out of a hard-nosed defensive slumber of the opening half.

"Shout out to Ezra Man – you're just a freak," Cleary said.

After the Broncos just scored in front of the posts in the final minutes before the half-time whistle, Mam put his side in front for the first time with a sidestep that fooled two defenders before his pace in front of the newly-named Cathy Freeman Stand beat fullback Dylan Stephens.

Mam again stepped through the Panthers line seven minutes later before a short dash this time ensured Brisbane a 18-8 lead in the 52nd minute.

Mam's second on the night inside the Sydney Olympic Park equalled the most tries in a year for a five-eighth with two modern-day contemporaries and another from 1910.

But the 20-year-old only had to wait a couple of minutes to break the record and own it outright in his own breakout season under coach Kevin Walters.

But this time it came down to Reece Walsh's much-vaunted sidestep that first worried the Penrith's tiring defence to set up an offload for Mam while closing on the tryline for his third score.

The Broncos seemed in disbelief of taking a 24-8 lead in a remarkable turnaround considering they missed the final eight last year and claimed the wooden spoon just another year earlier.

That may have accounted for their nerves in the first half that the Panthers seemed to have the better of exchanges, but didn't have a dominant scoreline to match.

The men from the foot of the mountains eventually scored first for a 6-0 lead after a lack of communications between Broncos backs and forwards cost them off a simple line dropout.

Cobbo uncharacteristically coughed off up ball 20 metres from Brisbane's line that put Ivan Cleary's men in range of scoring for the first time.

The rising star from Cherbourg could have counted himself unluck not to have scored or the Broncos to have gained a penalty after replays appear to show Panther winger Sunia Turuva block Cobbo's run on his way to the tryline.

Walsh was held up over the line critically on one occasion and knocked the ball on a couple more times.

There was an appeal led by the large number of booing Broncos fans in the arena for a penalty after Walsh collided hard with the Panthers' line coming through on a kick.

But when Walsh made one more error in dropping a live ball into his rivals' hands in the dying seconds, it sounded the end of one last twist to a game of many.