The 30-year-old won the New South Wales belt earlier this year, and had a fight lined up with Victorian giant Daniel America for the Australian title.
But the bout fell through after the 1.95m, 115kg America was knocked out by New Zealander Vinny Mahoni this month.
Instead, Nosa will fight Aucklander Sio Vitali for the vacant Oceania title in Melbourne on June 26.
It is the second time Nosa has had an Australian title fight called off.
He was meant to fight Felise Leniu for the then vacant belt last year, but his opponent sustained an injury and the bout was cancelled.
It was disappointing, but Nosa is expecting a torrid battle with Vitali, who fights out of the same Auckland gym as New Zealand K1 fighter Jason Sutton.
The tale of the tape is fairly even, with both fighters 1.83m tall, but Vitali is about 6kg heavier, at 108kg.
Nosa moved to Sydney in 2005 to further his kickboxing career, and is always introduced in the ring as hailing from Dunedin: "I'm always proud to let the Aussies know I'm from New Zealand."
Nosa played nearly 100 senior rugby games for Alhambra-Union and Zingari-Richmond, and was part of an Otago Boys High School First XV which shared the national secondary schools title with Rotorua Boys High School in 1998.
He played in a loose forward trio which featured former Highlanders lock Filipo Levi and All Black captain Richie McCaw.
Nosa, who was in Dunedin this month to support his brother, Godfrey, in his first boxing match, used to prepare for fights by kicking truck tyres and sandbags to harden his shins, but has since found a financially more rewarding way to get into shape.
The Sydney-based kickboxer has recently started a furniture removal business which is booming, despite the recession.
The downturn has forced some people to move to cheaper accommodation, and Nosa has been there to help pick up the pieces - well, the furniture.
"Everyone is downsizing, going from houses to units, so it is going well."
