Johnathan Thurston kicked a match-winning field goal to win one of the greatest ever NRL Grand Finals.

This ranks number one: Thurston

An emotional Johnathan Thurston had no hesitation in branding the Cowboys' maiden premiership victory as the biggest achievement of his career.

A man who has won World Cups and been a central part of the Queensland Maroons' dynasty that has dominated the fiercest rugby league competition there is for a decade was quick to answer where Sunday's 17-16 Grand Final win places.

Match report: Thurston kicks Cowboys to premiership
NRL Grand Final: Five key points
Cowboys player ratings
Broncos player ratings
Match highlights
Magic Moment: Feldt's late, late try
Magic Moment: Thurston wins it
WATCH: Winning skippers' speech
WATCH: Hodges' post-game speech

"It's number one. It's what you do. This is what you set out to do every year and I can't be prouder of the boys, the way they've gone about their business throughout the whole year," Thurston said.

"Whoever has come in to do a job for us has done a job and that was evident throughout the Origin period. We only lost the one game through that period and in the past that's where we've probably been our weakest. They deserve everything they get."

It almost wasn't to be – the crowd was stunned when Thurston's sideline conversion attempt after the fulltime siren struck the post – but the four-time Dally M winner made amends with an ice-cold field goal early in extra time.

"I was striking them really well yesterday so I was always confident of getting it, just didn't have enough swing coming back," Thurston recalled of the miss.

"I thought it was over for all money and a little bit shattered there when it didn't go over and you could probably see that on my face but as soon as the boys came over they snapped me out of it pretty quick and I knew I just had to concentrate on the next 10 minutes."

The premiership victory may confirm Thurston's place among the very best to have played the game but it wasn't his most complete performance – a crucial dropped ball in the first half allowed Brisbane to score a runaway try – and Thurston said his teammates rallied around him following that error.

"It was a tough error to take and the boys have rallied around me before and they snapped me out of it pretty quick," he said.

"It can be pretty daunting when you make an error like that and put your side under the pump and they made the most of it."

He said his field goal wasn't one of his best either, despite the feeling of inevitability that accompanied the play as soon as he received the ball in front of the posts.

"It came out of my hand pretty wobbly and didn't hit flush on the ground so I was lucky to strike it the way that I did," Thurston said.

"It was only that millisecond where I saw it go through and I jumped to 'Cootey' [Lachlan Coote] and it was mayhem after that."

In typical Thurston fashion though he refused to take credit for the win, or even contemplate its significance in terms of guaranteeing him a place among the pantheon of the greats.

"I'm just proud of the playing group. It's probably the most stable team I've been a part of at the club since I've been here," he said.

"All I know that I have to do is to prepare the best I can and do my role within the team and that's what I try and do. We've got players in the team that do their job and that's what 'Greeny' [coach Paul Green] instilled into the group when he arrived, was knowing your role and doing it to the best of your ability.

"Do I feel pressure going into games? No, because I know the players around me are well prepared and we can get the job done."