The two combatants faced off for the first time in Las Vegas on Friday (AEDT) with the height discrepancy between the pair startling.

Fundora stepped in after Tszyu's original opponent, countryman Keith Thurman, suffered a training injury and presents a bigger challenge - figuratively at least - standing at 197cm to the Australian at 174cm.

There is also more on the line for Tszyu in his long-awaited Vegas debut on March 30 (local time), with the chance to emulate his his legendary father Kostya as a unified world champion.

The Tszyu-Thurman bout was to have been a non-title fight but the Sydney slayer can now add the WBC super-welterweight belt to the WBO strap he already possesses.

Victory over Fundora would also set up a super showdown with undisputed welterweight king Terence Crawford, ranked the best pound-for-pound fighter in the world.

As soon Fundora was locked in, Tszyu's team flew in two new sparring partners, including 206cm southpaw rookie Mykal Fox, to replicate his lanky Californian opponent.

Despite less than two weeks' preparation, Tszyu said he would be ready to take down the 26-year-old giant, just like in the bible story.

"Two of them came down and grateful for the type of work they were able to give me," Tszyu said at a media open day in Las Vegas.

"A week's notice, a week's prep to fight such a fighter as that, it's David versus Goliath.

"This fight is awkwardness - you've got someone that's tall, lanky, whose got a completely different style to Thurman who I've been prepping for eight weeks - but nothing fazes me, nothing worries me.

"This is unification so there's another belt on the line, another legacy-defining type fight ... hopefully one day they will say the Tszyu name is the greatest family to ever step foot inside this boxing world."

Apart from height, Tszyu feels the "Towering Inferno" doesn't bring much else to the table.

Fundora (20-1-1, 13KO) was knocked out in the seventh round of his last fight, almost a year ago in Carson, California, by Brian Mendoza.

Coincidentally, Tszyu also met Mendoza in his most recent fight in October on the Gold Coast, successfully defending his WBO title with a unanimous points decision over the American.

Tszyu (24-0, 17KO) has been sparring with Mendoza while in the fight capital and says it didn't take much to floor Fundora.

"Mendoza caught him with a clean punch. It didn't take much, just a clean textbook left hook," Tszyu said.

"I asked him about Fundora ... he said he's awkward, his style, he uses his height in different ways but his punches don't hurt so I guess we will see on the night."

A laid-back Fundora says he hasn't had to alter his training for Tszyu, believing he's very similar to the fighter he was originally meeting on the undercard, Ukrainian Serhii Bohachuk.

"With Bohachuk, he's right-handed, shorter than me and a pressure puncher and same thing with Tim Tszyu - it's no different to me," said Fundora.

"I just need to stick to my plan and I will be successful."

He said he hadn't watched Tszyu's win over Mendoza and, despite his own loss, felt he had performed well before the knockout blow in an otherwise "easy" fight.

"I was in control of the Mendoza fight," he said.

"So I don't want to change too much because of the result, and it doesn't really matter to me what he did against Tszyu.

"I'm just going to keep focusing on my game."

Australian Associated Press