Sugar Ray Leonard, he's not ... yet. But Sonny Bill Williams saw off his third and most difficult opponent so far with a little bit of 'sugar' late last night.

Williams had been defensive earlier this week about the flurry of criticism surrounding his boxing and he needed to defend against his third and most difficult opponent in Australia's Gold Coast - Scott Lewis.

Lewis' main claim to fame was seeing off former NRL tough guy turned boxer Carl Webb.

However, he pressured and pestered the taller and heavier Williams in the early rounds before losing to a more skilled rival in a unanimous decision.

Lewis landed some troubling punches; pretty much the first real blows the former Kiwi and current All Black has had to wear. He sought refuge in a clinch more than once as Lewis tried to tag him with some clubbing shots.

It was his first real test - and Williams combatted the pressing Lewis with movement round the ring, his active left jab and keeping off Lewis with his much longer, pawing arms; while looking for an opportunity to land his right.

The fight began to turn in the third round, with Williams keeping his composure and starting to find his range against the bulldogging southpaw, never an easy proposition for a right-handed boxer.

Former world champion Anthony Mundine, a boxing stablemate of Williams, said during the week that he was amazed at the progress Williams had made as a boxer.

Certainly, for a man who had fought only three rounds before last night's six-round bout, Williams has not only good ring movement but showed an ability to slip punches.

Williams' jab did its job and he appeared to be ahead on points in the fifth round, with Lewis' left eye puffy and his punches becoming wilder.

Williams never seriously threatened to sit Lewis down and he may have to throw more punches in future bouts - but this was a good start in his first real fight against an awkward opponent.

Williams, who has captured New Zealand fans' attention as an All Black, has also copped plenty of curry for taking his eye off the rugby ball by pursuing a parallel boxing career.

But there was no sign of the stress fracture that may delay Williams' Super 15 debut as he moved around the ring, cutting down Lewis' attacking options.

He has yet to meet a boxer of real note or ability - but this was definitely a signal that Williams' boxing career could amount to more than a hobby.

Almost unnoticed with all the Sonny Bill hype was a fine debut by another New Zealander, cruiserweight David Aloua, who enjoyed an excellent entry to the moneyed ranks by knocking out the tough Jae Bryce in the third round.

Aloua, 23, is the Delhi Commonwealth Games amateur boxer controversially denied progress towards a medal when he lost his heavyweight first round bout against Kenyan Elly Ochola last year.

Furious members of the New Zealand boxing team protested when the fight was stopped late in the third and final round, with Aloua leading 7-5.

A medical official deemed Aloua couldn't fight on because of a bleeding nose, advising the referee to wave the contest off with 40 seconds remaining. Aloua appeared stunned.

Then New Zealand boxing coach Billy Meehan condemned the decision: "This is absolutely ridiculous, absolute garbage. The doctor must be about 90 years old and he's got absolutely no idea what he's doing. This is heavyweight boxing and our guy's got a bit of blood in his nostril. And it's not even flowing."

Meehan got a New Zealand medical official to inspect Aloua and he quickly ascertained there was nothing wrong with the 23-year-old.

"He's as good as gold and could go another three rounds," he said at the time. "The shame of it is that David was a genuine shot to go on and get gold here, a genuine shot."

Aloua was ahead smoothly on points early in that fight. However, the aggressive Ochola delivered a number of blows to the New Zealander's head in the third and final round, one of which knocked him to the canvas. The fight was constantly paused through the latter stages to let the New Zealand corner deal with Aloua's nose.

Last night, Aloua was pursued by Bryce, himself with only two pro fights, for the first round.

Aloua had a height and reach advantage over the squatter, stronger Bryce but his Australian opponent took the fight to him and slipped more punches through early.

It was halfway through the second round of four before Aloua scored with a heavy left but he began to find his range.

Both fighters were staggered in the third - Bryce by another Aloua left and then Aloua from an overhand right. But Aloua, showing composure and no small amount of character, rained in combinations until Bryce toppled and the referee stepped in.

New Zealand's Pakistan-born Kashif Mumtaz lost his light-heavyweight encounter with Australia's Daniel Baff - the second time they have met in two years - by unanimous decision after going the eight-round distance. Baff had won their previous bout.