Anthony Joshua was making strides in his fledgling professional boxing career when he was invited to Austria to spar with then-world heavyweight champion Wladimir Klitschko for 10 days in the summer of 2014.

Klitchsko liked what he saw.

"I haven't seen an athlete as athletic, as big, as fast, as talented as Anthony," Klitschko said of the 6-foot-7 (2.01-meter) Joshua, who at that time had won his first seven professional fights. "And if he's going to continue the way he is, developing himself, the future belongs to him."

Less than two years later, Joshua's time has arrived.

The easygoing Briton — with the "beach body" (his words), ferocious punching power, Olympic gold medal, and record comparable to Mike Tyson's early in his pro career — will announce himself to the world on Saturday when he fights Charles Martin for the American's IBF heavyweight title in London.

Joshua is taking a risk, having only had 15 professional fights, but the way he has dismantled all-comers in his fast-track climb to the top of boxing has him — and the rest of Britain — convinced he's up to the task.

"It's a long road we're about to go down," the 26-year-old Joshua said, a fierce determination in his voice. "We're only at the beginning."

Joshua took up boxing only in 2008, at the recommendation of his cousin. He was eager to find some discipline in his life while he awaited a court case that could have resulted in him going to jail for at least 10 years for what he has described as "fighting and other crazy stuff."

He was quickly hooked. He won medals at the English (gold) and world (silver) amateur championships, and won the super heavyweight class at the 2012 Olympics in London, his home city.

Joshua turned pro the following year and has needed just 32 rounds to beat his first 15 opponents by knockout.

"I'm going out there like a lion. I'm hungry," Joshua said in a telephone interview. "Right now, I've still got that underdog mentality to keep on proving myself time and time again. I'm not going to believe the hype."

The hype is in Britain, if not the rest of the world. Yet.

At home, Joshua is regarded as the most exciting and destructive heavyweight since his idol, Tyson, and potentially the best Britain has ever produced.

No previous boxer has won the world heavyweight title while being the reigning champion in Olympic boxing's biggest weight division — super-heavyweight. Muhammad Ali was the reigning Olympic light-heavyweight champion when he beat Sonny Liston to become world heavyweight champion.

"It's the ultimate double, really," Joshua said.

Seeing as the nickname of his opponent on Saturday is "Prince Charles," Joshua could easily be called "Prince Charming." He's been popular with the British public since winning Olympic gold, and embarking on a countrywide tour in his early professional career, helping build up an even bigger fan base. He has a warm demeanor and smile, and is respectful to his opponents.

While countryman Tyson Fury, the two-belt world heavyweight champ, is seen as one of boxing's "bad guys," Joshua is widely regarded as the opposite. He still shares a two-bed flat with his mother in north London, and his promoter, Eddie Hearn, says Joshua is learning Spanish at night class to help him relax, but also so he can curry favor in the Hispanic market once he decides to fight in the United States.

"There's something about Anthony Joshua," Hearn said on British broadcaster Sky Sports, which is showing the Martin-Joshua fight on pay per view. "It doesn't matter if you're a 25-year-old man having a pint in a pub or you're an 85-year-old granny doing your sewing at home, you just love this kid."

For now, Joshua has no interest in fighting in the U.S. He says the British boxing scene is booming — Britain could have two reigning heavyweight champions come Saturday — and is seeking his sixth straight win in the atmospheric, 20,000-capacity O2 Arena, where he also fought at the Olympics.

Joshua still has plenty to learn as a fighter. He was picked off a few times in his last fight, against Dillian Whyte for the British heavyweight title, and Fury says Joshua's "movement is terrible, and he's wide open with no idea how to defend himself."

"This game is not all about bodybuilding," Fury said last week.

But Joshua's punching power sets him apart.

"It's a blood-sport business," he said. "You want to go in and take someone's head off. People are paying for that."

While an amateur boxer, Joshua worked as a bricklayer and sold package holidays for an airline. His boxing career almost ended before it barely started when he was charged with possession and intent to supply cannabis in 2011. After pleading guilty, he was sentenced to a 12-month community order and 100 hours of unpaid work, which included chopping wood and helping pensioners with their gardening.

He's come a long way since.

"I've got to make the most of this opportunity," Joshua said, "because things could have been a lot different."