An Army truckie's golden sweep of all Australasian competitions in his first year as a black belt has baffled the jiu-jitsu community.
Despite facing heavier, more experienced black belts, Private Jung Kim won gold in State, National and Pan Pacific championships.
When an opponent is heavier and stronger, Private Kim plays guard game, using defensive techniques.
"Technique overcomes strength, but they are also a blackbelt and have decent techniques," he said.
"It's important to stay humble, avoid negative imagination, and be prepared for the unknown in a fight.
"I sweep him down first and then tap him out with ankle lock," he said.
But when an opponent plays guard game, he plays top game, trying to pass their guard.
"I use single under hook pass, paper cutter choke, knee on belly, top mount, then tap him out with Americana," he said, describing his favourite techniques.
46-year-old Private Kim started Brazilian jiu-jitsu 12 years ago for self-confidence, because he felt skinny and weak.
He recently moved up weight class to avoid fighting his coach, which meant he competed against opponents up to 10kg heavier.
"My coach said, 'see you in the final', but I didn't want to face my coach," he said.
He said he appreciated the support of his training partner, Corporal Anthony Zambory, and other members of his units, at 15th Force Support Squadron and 2nd Force Support Battalion.
White belt Flight Lieutenant Madelaine Wood started jiu-jitsu as a way to challenge herself, but received gold in the Pan Pacific masters division.
"I was super intimidated before I started, but it's been the most supportive sporting community I've experienced," she said.
Flight Lieutenant Wood said points were awarded for achieving dominant positions, the challenge being transitioning from focusing on submissions to understanding the point system in competitions.
"The final match was challenging; I couldn't secure a submission but won on points," she said.
Jiu-jitsu focuses on close-contact grappling holds and techniques, and the application of chokes and joint manipulations.
It was designed to enable a smaller, weaker person to defend themselves against, or even defeat, a larger and stronger opponent.
