The Olympic bronze medalist hustled for a career-best victory in his first completed 12-round contest but relished the challenge and showed smarts to stifle Masson's pressure-heavy style.

116-111, 115-112, 115-112 were the scores from their IBF final eliminator at New Zealand's Eventfinda Stadium and the fan favorite's positive body language at the final bell spoke of someone who knew the outcome was sealed.

The better man won and it was a morale-boosting victory, though Nyika will know he needs to be more defensively savvy and start faster against European champion Viddal Riley if he's to achieve his world title dreams next year.

Many rounds were proving close to score and naturally made for a tense watch given the stakes, one man enjoying spells of success before the other fired back. They took it in turns from that perspective, though Masson did well to push the pace late. Fighting like he trailed on the scorecards, a point deduction in the final frame felt decisive.

Referee Dave Braslow repeatedly warned the 34-year-old, first for low blows, then rabbit punching and his mouthguard coming loose in a disjointed affair. He appeared to spit it out the last time after an exchange in the pocket and could have no complaints, on an evening where he lacked the consistency to keep Nyika honest.

Masson (17-3, 9 KOs) timed Nyika well in the early going and pressed at the younger man's chest with combinations while attacking downstairs.

Nyika (13-1, 10 KOs) was caught too easily by the veteran's left hand and forced to take a backwards step in round two, after which the five-year pro finally established success behind his long levers.

Yet one-two punch flurries punctuated the opening minute of round three, where Nyika's defensive vulnerabilities were laid bare as he struggled to keep their fight at long-range.

That dynamic suited the southpaw nicely, though Nyika adjusted behind his jab in round four and their nip-and-tuck rounds persisted from that point forward.

Masson was perhaps fortunate to avoid further foul in the sixth as Nyika complained of a low blow that was called clean in real-time, having laughed off another instance three rounds earlier.

Having perhaps edged the seventh behind his jab and body work, Nyika lost his footing and fell awkwardly in the middle of a fiery eighth frame.

The 31-year-old shipped punishment and needed to survive Masson's onslaught in close quarters as you wondered aloud how smart these exchanges were for his chances of edging closely-contested rounds.

Nyika crunched a clever straight shot before boxing well and stifling Masson's better work in round nine, though their back-and-forth jostling for control continued in the tenth. Masson was warned a final time after his mouthguard came loose again, before a bruising exchange against the ropes to finish the stanza.