The 29-year-old professional kickboxer will fight Felise Leniu for the vacant Australian heavyweight title in Sydney next month.
Nosa, who shifted to Australia from Dunedin in 2005 to further his kickboxing career, was back in Dunedin for his brother's 21st celebrations.
Nosa has had 27 fights for a record of 18 wins, seven losses and two draws.
Ten of his wins came by way of knockout and he is the seventh-ranked heavyweight in Australia.
The fight with Leniu is the biggest of his career.
The Auckland-born Niuean will enter the bout as a firm underdog and is giving away a significant weight advantage.
Both fighters are 180cm tall but Nosa is lighter than at any time in his career, weighing in at 97kg.
That is relatively slight compared with Leniu's 115kg.
Leniu has been in the ring with some quality fighters, including Australia's No 1-ranked kickboxer, Peter Graham, and is known for his power.
"Hopefully it will be a good fight," Nosa said.
"He's a good fighter with heavy hands, and he is a big bloke, too. I think it is a fight that a lot of people will be wanting to see."
The pair are mates but will be putting aside their friendship when they step in the ring.
"He's a really nice bloke but we both agree that it is a sport and it will be all business once we put on the gloves.
"It's like any sport. We still respect each other, and at the end of the day, after we've beaten each other up, we'll have a beer together and a bit of a laugh."
Kickboxers use their shins to strike opponents when kicking and Nosa has been hardening his by sparring with truck tyres and the odd sandbag, and even ropes wrapped around a column serve the purpose quite well.
His lower legs bare the scars of those encounters but are nice and "numb" now.
Before Nosa took up kickboxing he played nearly 100 senior rugby games for Alhambra-Union and Zingari Richmond.
He was also part of a talented Otago Boys High School 1st XV which shared the national secondary schools title with Rotorua Boys High School in 1998.
Nosa played No 8 in a loose forward trio which featured former Highlanders lock Filipo Levi at blindside and All Black captain Richie McCaw on the openside.
Otago captain Craig Newby scored a try for Rotorua Boys.
Nosa joined the "brawn drain" three years ago after being approached by Bulldog Gym in Manly to join them and fight professionally.
It had long been a dream of the articulate but softly spoken athlete.
But after three years of fighting professionally in Australia, Nosa is keen to return to Dunedin next year and work towards another dream - setting up a gym for disadvantaged Maori and Polynesian youths.
Nosa says sport has been a big influence on his life.
It has taught him focus and given him discipline and self-respect.
Those are lessons he is keen to pass on.
