The way Sonny Bill Williams sees it, taking on an oddball Kiwi boxer shows how serious he is about earning an All Blacks rugby jersey.

It may sound like an unusual approach - but then again, not much has made sense in the build-up to Williams' second professional bout on friend Anthony Mundine's boxing undercard in Brisbane on Wednesday night.

First his heavyweight opponent - the obscure Ryan "Hulk" Hogan - failed to show at Monday's press conference.

And when he finally did appear at Tuesday's weigh-in, the beefy Aucklander came out of nowhere to jostle Mundine off the scales before running away, much to Williams' bemusement.

Critics would be forgiven for dismissing Williams' fight as a joke following Hogan's antics.

But the ex-NRL star vowed to have the last laugh after declaring an intense boxing training program had him primed for not only the fight but also his much-anticipated 18-month New Zealand rugby stint.

Williams will take his first step toward achieving his goal of 2011 World Cup All Blacks selection when he makes his debut for leading province Canterbury in the national championship on July 30.

"People think I am not serious about my move to New Zealand," said Williams who spent the last two years at French rugby club Toulon.

"(But) the evidence is here (with) ...the tough boxing training.

"It's my off-season. I could be just laying on the beach but I have chosen a great night to be involved in and it keeps me on my toes, keeps me fit.

"I just want to go over there (NZ) and prove that I can play at this level."

Mark Gasnier this week became the latest rugby convert to return to the NRL, saying he'd missed league.

But Williams claimed he wasn't feeling any pangs, not any more anyway.

"Not as much as my first year in France. The second year in France I really started enjoying myself and loving the sport (rugby)," he said.

"One day in the future maybe I will go back to league because that is where I got my name from and I will never forget that.

"But at this stage I am loving what I am doing and very excited about the new goals I have set myself. I am going to New Zealand to try and do something."

Williams also did not rule out continuing with boxing in the future despite his unorthodox introduction to the professional ranks.

The lead-up to his debut last May in Brisbane resembled a circus.

His opponent - Gary "The Baboon" Gurr - lived up to his name and gatecrashed, then tried to trash, their press conference before causing another scene at the weigh-in.

Williams won his professional debut when the fight was stopped in the second round of their four round bout in Brisbane.

Now Williams takes on Hogan, a fighter of similarly limited pro experience, who is said to be from the "mean streets of Auckland".

"That was the first I had seen him," Williams said.

"He may be getting cold feet - it (running away) was pretty rude."

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