Fundora plans to treat himself with donkey after Tszyu

Sebastian Fundora is used to proving the doubters wrong with the lanky Californian out to upset the boxing world order by taking down Australian king Tim Tszyu.

The 26-year-old got the call-up to fight Tszyu, with two super welterweight belts on the line in Las Vegas on Sunday (AEDT), after injury to the unbeaten Sydneysider's original opponent Keith Thurman.

Standing 197cm or 6ft 6 in the old school, Fundora breaks the mould as a 154lb division fighter and is an incredible 23cm taller than Tszyu.

Fundora said right from when he was eight-years-old and started boxing he was told the sport wasn't for him.

"The owner of the gym that I trained at, he used to tell me all the time you should play basketball," Fundora said.

"I think with time people are realising what I am and why I should be in the sport."

But it's more than his height that's different about him.

While he's a non-drinker, he loves burgers and pizzas, hates social media and considers his father and trainer, Freddy, and younger sister Gabriela, who won a boxing world title this year, as his best friends.

Fundora says he bought a farm in the hills around the southern California desert town of Coachella and his plans post fight include getting a donkey.

He lives there with his parents, five siblings and eight dogs.

He doesn't wear the gold jewellery popular with some boxers and said he can't buy a flashy car because it wouldn't make it up the hills.

"All those things are expensive," Fundora said.

"I bought my house last year and I have 20 acres and plan on getting a donkey and I've paid off my trucks and I'm financially stable and I'm very happy where I'm at.

"I can't drive no fast car as I live on the mountain so I was planning on getting an Audi but then went out the window so I will just focus on my donkey and maybe some horses."

He's only lost once in his 21-fight professional career - the defeat coming last year against fellow American Brian Mendoza - and says he's up to fighting world champion Tszyu.

"I'm ready - I only have that one loss," he said.

"I was already fighting for the WBC vacant and they knocked on my door and I answered.

"I don't know about the others but I answered."