Its been a golden month for Osbourne (18), a surveying student, who was second overall and the first New Zealander home in the junior elite section at the Oceania championships in Wellington two weeks ago.
The event also piggybacked the national championships, allowing him to lift the national junior title.
Despite admitting he tapered off a little in yesterday's sprint course involving a 750m swim, 20km bike ride and 5km run, Osbourne appeared to have lost none of the class that saw him feature in the Oceania event.
Shaking off the effects of an obvious autumnal chill, Osbourne snapped into his work around 300m into the swim and held a 40sec advantage going into the cycle section.
He maintained that advantage through the cycle stage and extended it on the run.
He held a 1min 21sec lead midway through the stage and broke the finishing tape in 1hr 1min 3sec, and 2min 16sec clear of second placed Chris Bisley, with Neville Thorne third in 1hr 3min 55sec.
Osbourne described his race as being done at tempo pace.
"I don't think I warmed up the whole race, he said of the airy chill.
"So I was comfortable at tempo pace. I knew I could take it if I was pushed."
National ironman representative Chris Bisley, who settled for second place, but picked up his first open men's triathlon title, due to Osbourne still being a junior, was full of praise for him.
Osbourne will now be focused on the world championships in Budapest, Hungary, in early September, where he will be competing in the elite junior section.
Taryn McLeod burst away from the transition from the bike to the run with a turn of speed that broke a three-way deadlock with Laura Smit and Deborah Lynch to secure her fourth Otago triathlon title in open women's competition, in 1hr 5min 29sec.
Initially, it was a four-way battle, with McLeod, Smit, Lynch and Rebecca Grant all locked together entering the cycle stage, but misfortune struck Grant when the gears on her bike failed, forcing her withdrawal.
McLeod (28), by her own admission is taking a back seat in the sport, because of work and study commitments, but still appears not to have lost her competitive edge.
Despite the running stage yesterday, breaking her from the shackles of Smit and Lynch, she found the sensation of running on cold feet a little weird, as at no stage had she warmed up in the race itself, due to the pre-winter chill.
This had an affect more so when it came to the running stage.
Such was McLeod's dominance on the run that she opened up a gap of more than a minute on Smit, who finished second in 1hr 6min 32sec, with Lynch third in 1hr 7min 1sec.
