We have a new premiership favourite after an epic opening weekend of the NRL finals series.

But the Brisbane Broncos’ brilliant surge to the preliminary final comes with a caveat after a major boilover 24 hours earlier.

Brisbane outlasted North Queensland Cowboys 16-12 in a gripping, gruelling Queensland derby in front of a 50,388-strong home crowd on Saturday, overcoming several bogeys in the process.

• Cronulla beat Rabbitohs, book date with Cowboys 
• Broncos buck Cowboys, set up home prelim 
• Bulldogs slay Dragons in golden-point thriller

It was the Broncos’ first finals victory since 2011 and their maiden post-season win over ‘little brother’ in four showdowns.

Meanwhile, coach Wayne Bennett vanquished a remarkable hoodoo, notching his first finals success at Suncorp Stadium at his eighth attempt.

But Melbourne’s equally stirring 20-18 defeat of former bookies’ fancies, Sydney Roosters, on Friday night may have taken a tiny bit of the sheen off a watershed weekend for the Broncos as they aim for their first grand final appearance since 2006.

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The result puts the Broncos and Roosters – who produced arguably the finest match of the year in Round 24, won 12-10 by the Tricolours – on a preliminary final collision course, provided the minor premiers can win their semi-final grudge match against Canterbury on Friday.

Johnathan Thurston feels the pain after losing a thrilling Queensland derby. Photo: Getty

It means the regular season’s two top teams can’t face off the grand final.

On a positive note for the Broncos, if they do face the Roosters in week three (and the September specialist Bulldogs can’t be counted out by any measure, despite a scratchy showing in their golden point triumph over St George Illawarra) it will be in their Brisbane backyard, instead of an ANZ Stadium decider in Sydney.

And Bennett’s charges showed what an advantage it is playing in front of the Suncorp faithful, who spurred their heroes on against the Cowboys in a high-quality nail-biter marked by defensive intensity from both sides, despite the array of glittering attacking talent laced through both line-ups.

The Broncos largely nullified the NRL’s No.1 player, Johnathan Thurston, and repeatedly shut down his trio of lieutenants, Michael Morgan, Lachlan Coote and Jake Granville.

The home side’s goal-line defence was as good as anything produced by any team in 2015, while Andrew McCullough (61 tackles), Matt Gillett (50) and Sam Thaiday (40) got through a mountain of work.

Ultimately, the match came down to Brisbane’s ability to capitalise on rare offensive opportunities – and it was the club’s burgeoning young halves that did the damage.

Ben Hunt, making just his second start in a finals match, flashed over for the only try of the first half via a dazzling 30-metre solo run.

Anthony Milford marked his maiden post-season appearance by backing up slick work by interchange livewire Kodi Nikorima and racing away for a decisive try in the 67th minute when the match was in the balance.

Michael Ennis was inspirational for the Sharks, but will he be free to tackle the Cowboys? Photo: Getty

The collective performance of Hunt and Milford emphatically answered a question mark that was lingering over the Broncos’ title bid; this playmaking duo – after a rusty start to the year – are as good as any halfback-five-eighth combination in the competition.

While the loss has dented the Cowboys’ aspirations, they now find themselves on the (slightly) easier side of the finals draw.

Thurston and co. will regroup for a fascinating Saturday night clash at home against Cronulla Sharks, who extinguished South Sydney Rabbitohs’ ailing premiership defence in a resounding 28-12 rout on Sunday.

The Sharks have beaten the Cowboys twice in the past three months, but face a nervous wait after key man Michael Ennis found himself on report for a high tackle in the latter stages.

Neither club has won a premiership and the ghosts of failed finals campaigns past will permeate through next weekend’s Townsville pressure-cooker.

The winner will then head to Melbourne in week three, taking on the dark-horse Storm – a formidable proposition, no doubt, but can Cam Smith, Cooper Cronk and their henchmen go to another level after their successful Sydney hit-and-run mission?

The Bulldogs could also feel the wrath of the judiciary after Kiwi Test forwards Frank Pritchard and Sam Kasiano were both censured over an ugly incident involving Dragons pivot Gareth Widdop.

Encouraging the four teams that are preparing for sudden-death clashes in week two is the extraordinary statistic that in 18 seasons of eight-team finals series, the two sides that progressed straight through to week three have both won their preliminary finals just four times.

Whichever way you break it down, there’s six teams left and a compelling premiership case can be made for all of them.

The Broncos’ new-found top billing is deserved, but arguably their biggest test of all awaits a week before the grand final.