Anthony Joshua turned to boxing for salvation and the London 2012 Olympic gold medallist is confident of beating Dillian Whyte after his opponent's attempt to assassinate the character.

The London heavyweights meet for the British and Commonwealth titles at the O2 Arena on Saturday night, with Whyte calling Joshua a "fraud" and a "robot" in the build up.

Joshua's troubled past has been well documented - in 2011 he avoided a jail term for possession of cannabis after being found not guilty of attempt to supply - but he revealed he once had to wear an electronic tag and boxing has allowed him to change his lifestyle.

"Boxing is the easy part," the 26-year-old said. "I never had any intention of being a boxer. I just wanted to get bigger and stronger.

"I was looking at a jail sentence so my only ambition was to be found not guilty. That was it.

"When I got past that and found not guilty I carried on boxing.

"I get to meet people I would never have got to meet before. I've met good people, changed my lifestyle and mentality."

Joshua declined to comment on the offence which led to the electronic tag, which monitors the whereabouts of a person who is under curfew.

"That was part of my story and I'm here now and that's all that matters - I'm still going strong," he said.

So strong is Joshua, who gave up a job as a bricklayer to go to a training camp in Las Vegas, that he is talked of as a future world heavyweight champion.

"I still won't say I'm going to be heavyweight champion," he added.

"I'd love to, but I'd rather get it and show you instead of talking about what I'm going to do."

He lost to Whyte as an amateur in October 2009. It was his third fight and his first two had been won by knockout.

He said: "I lost again at the Europeans and at the Worlds. You have to learn from those and you cant get too ahead of yourself."

And Joshua knows he must be on his guard to avoid falling to another defeat to Whyte, who is undefeated in 16 fights, 13 by knockout.

Joshua, whose record is 14-0, all KOs, said: "Heavyweights in the top 100 - I promise you they've all got knockouts on their records.

"We all possess power. (But) I know what he possesses and what I've already dealt with so I think I should be okay."

Whyte, for his part, also has a chequered history and served a two-year suspension after testing positive for controlled substance methylhexaneamine following a fight in 2012.

The former kickboxer attributed the doping offence to a simple mistake, unknowingly taking the banned substance in an over-the-counter nutritional product.

"A lot of people would have jacked it in, because it's hard," the 27-year-old said.

"Within 12 months of being back (from my ban) I am here.

"I lived off my savings (during the suspension). It was hard. I had to penny pinch but when you have a dream that you are so passionate about and so determined to achieve it, you do what ever it is you have to do."

Whyte discredited Joshua's previous opponents in predicting an upset.

"He's been fighting old men with lots of losses on their record," Whyte said.

"The difference with me is my mind set. I have my own ambitions and he is in my way.

"I am going to try to take away everything that he has and I think he will fall apart."