He is the four-legged secret weapon leading the Brisbane Broncos' stampede towards this year's NRL premiership.

Buck has been a regular feature at home games in Brisbane for the past five years, along with his trainer and rider Natalie Siiankoski.

Despite the noise, action and crowds, the dynamic duo support the players and encourage the fans along the sidelines.

Ms Siiankoski sourced the calm stockhorse from Australian Outback Spectacular — a live action dinner show on the Gold Coast — to ensure he had experience with a crowd.

"He [Buck] had a background with performance and he was used to a crowd, not as many as 30,000 to 50,000 screaming fans but he had experience with crowds," she said.

"Buck knows that everyone is looking at him and he knows when it's his time to shine ... he loves it, he loves his job."

Ms Siiankoski is a Brisbane-born Australian equestrian champion.

She became involved with training and riding Buck after promotions work at the Wynnum Football Club.

"We applied when the former Buck was retired and the Wynnum Club CEO knew my horse background and he put an application in for me and the rest is history," Ms Siiankoski said.

Buck eats grass on game day ahead of arriving in Brisbane for the Broncos semi-final. ( 612 ABC Brisbane: Jessica Hinchliffe )

Training for game day

On game day Ms Siiankoski rides Buck at home on a 10-acre block at Tamborine, in the hinterland area between Brisbane and the Gold Coast, before he is bathed and brushed.

"I make sure he is smelling and looking his best," she said.

"We then pack the truck and make sure we have everything, including feed, and get on the road with enough time to battle the crowds on the way in.

"It is not just about rocking up to the game."

Buck is trained four times a week, which includes a schedule of dressage and jumping.

"Buck's very versatile, some days we will also practise his bows as he likes to keep things interesting," she said.

During the off season, radios are set up in Buck's stable to keep him exposed to noise.

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For the love of the fans

When trotting down the tunnel at Lang Park before a game, Ms Siiankoski said Buck knows he is about to go on show.

"Once he hears the Broncos song at the start he knows it's time to go; he knows once that music starts we head out and off we go," she said.

"You can tell he loves it... he's in his element.

"It's much better when the Broncos are scoring lots of tries, he loves it a lot more when he's out and about."

The duo's job includes encouraging the crowd to get involved in the game.

"You can have the tinniest kid, to an adult, to a grandpa and they all just love him ... everyone's face has a smile on it when I walk up to them with Buck," Ms Siianoski said.

"At the end of the day it's about getting everyone involved and getting behind the boys.

"The fans always give him a good cheer when he goes around."

The excitement of game day

Not only does Buck have to look out for touch line referees, he also has to avoid pyrotechnics.

"We have only had a couple of hiccups over the five years; a couple of pigroots down the side and he did buck a couple of times," Ms Siianoski said.

"Flames he had not seen before startled him too.

"They went off one more time than we thought they would and it was close to where he was ... he thought the devil was coming after him.

"We have certainly had to stop for the ball boys a few times, both me and Buck."

Buck bows to the camera at feeding time with rider Natalie Siiankoski and her newborn daughter. ( 612 ABC Brisbane: Jessica Hinchliffe )

Buck is one of a kind

Ms Siianoski held Australian titles in equestrian long before Buck came along and continues to train today.

"From 2004 to 2008 I was part of the Australian A squad leading up to the Beijing Olympics," she said.

"I did not quite get there, but it was an experience along the way.

"I returned to the squad in 2012-2013 and then we have welcomed a little lady into our lives with our first born, so the past 12 months has not been quite as exciting on the competition scene."

Juggling a newborn and heading to every Broncos home game is just a part of life now for Ms Siianoski.

"You have to be super organised on game day, but everything gets done that needs to be done," she said.

"I'm pretty over the moon the boys have made the final, and Buck is always excited once we get to the game.

"For me it is a fun job ... it helps too that Buck is one of a kind."