Ahead of his world title unification fight in Las Vegas, Tim Tszyu has the big guns of boxing queueing up, declaring his rivals can "come to papa".

Tszyu will take on lanky American Sebastian Fundora on Sunday (AEDT), attempting to add the super welterweight WBC belt to his WBO strap and become a unified world champion like his Hall of Fame father Kostya.

The unbeaten Australian is already reaping the rewards of his dogged road to superstardom, with former unified welterweight champion Errol Spence Junior tweeting that he was "Headed to Vegas - I want the winner!!", adding a video of a shark to illustrate he was the hunter.

Pound-for-pound king Terence Crawford is also reportedly in talks with Tszyu's camp about a mega fight should the "Soul Taker" do the job against Fundora.

Crawford stopped fellow American Spence in the ninth round of a blockbuster last July to become undisputed welterweight champion, but both are looking to move up a division.

Tszyu said that once he had taken care of Fundora, his next move would be the one that made the most financial sense.

He said he was enjoying that the script had flipped and he was now the big name being called out.

"I've wanted Errol Spence for a long time, we've had history and he's called me a few things, so I would love that fight as well," the 29-year-old said.

"Come to papa ... it feels good and that's the reason why we went down the path of getting the belts because they come to you.

"I was in a position where I was chasing, chasing, chasing (Jermell) Charlo, and now they're coming to me.

"These are the moments that I've always wanted, to get the big names into a fight."

Tszyu (24-0, 17KO) will start as heavy favourite against Fundora, despite giving away 23cm in height and 24cm in reach, with the American knocked out in his last fight by Brian Mendoza, who Tszyu then beat.

The Australian admitted Fundora's height made it stylistically the most awkward fight of his career, but referenced heavyweight great Mike Tyson's long success against taller opponents.

"It could be the toughest, it could be the easiest, you never know," Tszyu said.

"Of course he's got height, but we all bleed the same blood.

"I'm taking inspiration from Mike Tyson and everything he did into this fight.

"He (Fundora) is coming in for the brawl and he's good at what he does and it's all about eliminating what he does and showing what he's not good at.

"This is step one to where I want to be. There's plenty of big super fights to be made in the near future."

The Sydney slayer questioned the professionalism of Fundora (20-1-1, 13KO) after the Californian was spotted out in the hotel eating burgers and fries for lunch, then pizza for dinner.

"True professionals don't do that," Tszyu said.

"I'm in shock, a professional athlete who is two days out from his fight is eating sh** like that, it baffles me."

Fundora said what he ate and how he prepared wasn't the Australian's business.

"I don't think anything I do should bother him, it's not affecting him," the 26-year-old said.

"I can eat burgers and pizza ... am I not allowed to enjoy myself?

"I've got a fast metabolism and I work hard - I've never missed weight, so 'unprofessional', that's a poor choice of words."