Tim Tszyu is left stunned by his giant opponent's 's**t' act just before their world title fight: 'Professionals don't do that'

Tim Tszyu has branded Sebastian Fundora unprofessional after being left shocked when he heard a detail about the giant American's preparation for their title fight in Las Vegas on Sunday.

The Australian will be giving away an incredible 23cm in height to the American as they clash for the WBO and WBC super-welterweight titles at the MGM Grand casino - but a telling detail shows their lead-ups to the fight have been radically different.

Tszyu had seen photos on social media of Fundora eating junk food just two days out from the bout, and before the pair weighed in.

'Fundora having pizza, having burgers - I was in shock,' Tszyu said on Friday, Australian time.

'As a professional athlete, two days out from his fight and he's eating s**t like that? It baffles me.

'I live and breathe this sport and I live by that code of the disciplined lifestyle.

'Professionals don't do that.'

Before the junk food revelation became public, Fundora gave an interview detailing his usual pre-fight diet, saying he eats three eggs and a bacon tortilla with green salsa for breakfast, pasta with meat sauce and garlic bread for lunch - and 'if it's up to me' steak and hot chips for dinner. 

The American boasts about his fast metabolism, which enables him to make the 69.85kg limit for the super welter division despite standing an amazing 197cm tall.

On the other hand, Tszyu has his own fight chef, Omar Iferd, who makes sure he eats nutritious meals as he strips down to make weight.

A win over Fundora will open up some very important doors for Tszyu, who is on the verge of securing some huge fights.

This week former unified welterweight champion Errol Spence Junior tweeted that he was 'Headed to Vegas - I want the winner!!', adding a video of a shark to illustrate he is hunting for Tszyu. 

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.'