Anthony Joshua: Schooling himself on diet of Ali, Lewis and Klitschko after his 'rubbish' Olympic gold medal

Before his second pro fight, Britain's heavyweight hope tells Kevin Garside how much he has learned in a short time

Joshua at the London 2012 Olympics (Getty Images)

Returning to the gym where it all began is ordinarily a moment of nostalgia for professional boxers. These old houses of sweat and pain are often tucked away down side streets, behind shops and car-repair units. They do not invite casual interest. Finchley ABC is typical: small, congested, faded interior dominated by a battered old ring. Weights are casually scattered where they fall in ante-rooms that double as changing areas. And from ceiling beams or metal supports heavy bags frame the available space.

This was home to Anthony Joshua. And if it seems like yesterday that he first walked through the door, that is because, relatively speaking, it was. Joshua is only one fight into his professional career. Saturday night, in bout No 2, it is Paul Butlin's turn to experience the sledge-hammer right that took Joshua to Olympic gold in London. The more Joshua reflects on that remarkable moment, the more surprised he is at the distance travelled. The more he learns about boxing, the more he realises how little he knew 15 months ago, and how far there is still to go.

Joshua was 18 before he first wrapped a fist in leather. There is about him a disarming sense of his not being worthy of the company he keeps. To journey from rank inexperience to Olympic gold in five years is a staggering achievement. He required luck along the way but none more than he deserved for taking on the challenge in the first place. Ask him now if he is any good and he laughs. Don't be silly. But none of this frank appraisal about his level disturbs him. It does not stop him climbing through those ropes. And this is what makes this fellow special, and dangerous. He has what Audley Harrison so demonstrably lacked: unshakeable self-belief shot through with commitment.

"One thing I do know looking back at the Olympics is that I was rubbish. I'm still rubbish now but in the Olympics (below right) I was a bad, bad fighter. I feel that even more so now. In the amateurs I was fighting opponents who had way more experience, 200 bouts some of them. But I had no fear. Once I sign up for it and I'm on that plane there is no turning back. I do my work. In the gym and on the mental side I make sure I have that all straight. I never cut corners. Whatever happens in the ring it's down to me. In the amateurs my attitude was: there is another man in the opposite corner, all he can do is beat me, and I'm not going to let that happen. And that's how it was."

It is only three weeks since his pro debut. He might fight five times by Christmas. This is the old-school route. Mike Tyson chalked up 18 bouts in his first year as a pro. This was partly to keep him out of trouble, of course. Tyson was sprinting from a troubled past and was grateful for the positive feedback he gained in the ring. Joshua was never in Tyson's league of teenage tyranny but he had his moments. "I remember walking to college, there was this guy, I must have looked at him, he looked at me. It got rowdy, I didn't back down, he didn't back down and it turned into an altercation.

"Afterwards we spoke. He said: 'I was in a bad mood. You are a big guy and you know what? I just needed someone to whack.' If you are a big guy, either people love you for it or they are threatened by it. I realised that you get in trouble for street fights. In the ring I get praised for hitting someone. I prefer getting in there, competing with someone and getting a pat on the back to running from the police afterwards, which pretty much sums it up."

At 6ft 6in and 17st-plus Joshua is an impressive lump of naturally occurring musculature, and an obvious set of shoulders on which to pin sponsorship money. Enter LA Muscle, for whom Joshua will spread the message over the coming 12 months and beyond. This is taken in his stride, another opportunity afforded him courtesy of his athletic gifts. Cast your eyes around the gyms of elite sport, particularly rugby, and observe how hard participants have to work to look like Joshua. But big arms won't save him in this game, a lesson he learned early on.

"When I first started, there would be about six heavyweights in the gym. I used to get in there but I was easily hit. I was getting battered. I was thinking, 'You know what, something has to give here'. I started to watch Ali, seeing how he slipped shots, learning more about the game. I brought my hands up. They used to be way low. I realised that boxing is not so much about hitting people as not being hit. And it's not all about the hands, it's about the feet as well. I used to think it was all about raw power from up here [points to arms], but I learned that you get your power from your legs and your feet. I'm still learning this stuff now. You can imagine how I was five years ago, so raw."

The 14 months between gold and pro debut were spent in the gym working at his trade. He canvassed opinion from the great and the good; spoke to David Haye, corresponded with Vladimir Klitschko and is in regular contact with Lennox Lewis. "Lennox gives me technical advice. He took time out to speak to me, which is really cool."

The path Joshua has chosen is about as hard as they come. Ask Harrison, who had the same physical advantages and the same gold medal, but could barely get past go.

Despite the body of work delivered by Lewis, the stereotype of the Limey heavyweight projects a boxer inflated by hype and compelled to fail. Even in victory Frank Bruno could never quite escape the panto caricature, no what I mean 'arry. Joshua is humble, modest and quick to learn. "People are waiting for the next Ali. They don't say, 'oh he's good.' They say he is no Ali. They write you off. You live your life on the edge in boxing. One fight can determine your whole career.

"To be great and stay there you have to have something no one else has. I can't say if that is me until I get there. If I can do as a pro what I did as an amateur I will be over the moon. The desire to prove myself is massive. I was out of the ring for 14 months. It's time to get the ball rolling."

Anthony Joshua uses La Muscle as part of his training and nutrition plan (lamuscle.com)