By Martyn Herman
LONDON (Reuters) - As flashbulbs illuminate his cast-iron torso in a gym wedged under a railway arch near London Bridge, Anthony Joshua paws at a punchbag with considerably less force than he used to demolish his first dozen opponents.
The 25-year-old then levers himself into the ring and is introduced as "the future heavyweight champion of the world" by a suited executive from the latest company to sign up the Londoner heralded as British boxing's next big thing.
With 12 knockouts in 12 fights, all inside three rounds, since leaving the amateur ranks and moving into the shark-infested waters of professional boxing in 2013, Joshua is hearing those kind of endorsements quite often.
Reigning three-belt world heavyweight champion Wladimir Klitschko, another former super-heavyweight Olympic gold medallist, recently sparred with Joshua and described him as the "future" of the division.
With the heavyweight section crying out for a box-office fighter after years of unspectacular dominance by Wladimir and Vitali Klitschko, no wonder eyes are turning to Joshua.
Two metres tall, packing 106 kilos of pure muscle and a smooth mover, he looks the part. He says, however, that he is a learner in the toughest of all trades.
"I'm not going to start piping up and shouting myself from the rooftops," he told Reuters in an interview. "Whatever Klitschko says about me it's all just potential until I make it a reality.
"I've got a world champion backing me so that's great. I must be doing something right but my job now is to do something extra to make that a reality," he added at an event arranged by ORS Hydration Tablets.
"Right now I'm crawling, they're seeing if I can walk and once I've started to walk they'll see if I can run, then after that we'll see how high I can fly."
Joshua handed out his latest beating to Brazil's Zumbano Love last weekend but his next fight, against seasoned American Kevin Johnston at London's o2 Arena this month, is the start of phase two of the Briton's education.
KNOCKOUT PREDICTION
Johnson, 35, went 12 rounds with Vitali Klitschko in 2009, has never been stopped in 36 fights and predicts he will knock out the Londoner.
Joshua seems genuinely excited by the prospect of being able to showcase more than just his power, even if he knows in the professional game "you cannot afford to lose".
"He is just another guy I'm going to knock out," he said of his 13th opponent. "But Johnson is someone I can work with.
"He will cause me some difficulties but I will be able to prevail. I can't display my attributes in a round or two. If we start going four or five and he's in my face then we'll see that. I actually wanted my last fight to go longer.
"I was a latecomer. I'm still learning my trade. But then there is pressure to advance isn't there? I'm between a rock and a hard place. The main thing is to win because pro boxing is a lot different to the amateurs, you can't afford to lose.
"If Johnson knocks me out, they'll say 'Look I told you, he's not that good after all'."
There is a cautionary tale. That of Audley Harrison.
He claimed the super-heavyweight Olympic gold medal at Sydney 2000 and then won his first 19 pro fights against a motley crew of no-hopers and journeymen before the losses started piling up.
Harrison fought for the world title in 2010 but was knocked out by David Haye, throwing only one punch in a contest that lasted less than three rounds.
"I think Audley was a different animal, he was a lot older than me, he didn't hit and move, he didn't adapt, but he did well, he was an Olympic champion," Joshua said.
While Harrison's pro career was forgettable, Wladimir Klitschko, who could soon face British champion Tyson Fury, says Joshua could be the man to fill the void once he has hung up his gloves.
"I haven't seen an athlete as athletic, as big, as fast, as talented as Anthony and if he's going to continue the way he is, developing himself, the future belongs to him," he said.