Former rugby league player turned pro-fighter Tai Tuivasa's message after his stunning UFC debut was simple: "I'm here to stay."

The Panthers and Roosters junior claimed victory over American Rashad Coulter via a first round knockout, as he predicted, but it was not with a punch, but rather a flying knee – a remarkable move for a heavyweight.

Bam Bam: Tai Tuivasa soaks in victory. Credit:Chris Lane

"I saw his head and I was like 'I gotta give this a go' – and I did it, he went back and I'm like 'oh shit it worked!'"

"Bam Bam" entered the ring to a rousing rendition at Qudos Bank Arena, with Vanessa Carlton's A Thousand Miles blaring, an Aboriginal flag draped around his shoulders and mentor Mark Hunt in the front row.