By Matt Christie

Every boxer who reaches the top will be able to look back at their journey and name fights in which they were forced to dig deep to progress, to answer questions they never knew existed, and in some cases, rebuild and start again.

Herculean heavyweight superstar in the making, Anthony Joshua, could be set for such an encounter at London’s O2 Arena on Saturday night when he tackles his long-term enemy, Dillian Whyte.

The pair have history, and if you listen to Whyte - an unbeaten 27-year-old who has flattened 13 of 16 professional opponents – the hype around Joshua is inflated nonsense that his potent fists will puncture.

After all, he’s beaten the supposedly invincible man before.

Back in 2009 when were both finding their way as amateurs, the pair engaged in a thrilling barnburner which saw the wild and ragged Joshua sent careering into the ropes in round one, and dropped by a left hook – still a Whyte honey punch – in the second.

What he achieved following that points defeat is testament to the Watford hero’s dedication to his trade.

After another 42 contests, three years, and only two subsequent defeats, Joshua was Olympic champion and rightly regarded as one of the hottest prospects in world boxing.

The 26-year-old is infinitely better than he was back then but not one of his 14 professional opponents (all bombed inside schedule) came into battle with Joshua with the self-belief, or physical gifts, that Whyte brings.

To the hardcore, Dillian is well known.

He jabs from the hip with his long arms, moves elegantly for a man of his size, and delivers curling unsighted blasts at haste.

In short, he is a threat, and a live underdog. For the first time in his career he will face a fighter he knows has beaten him before, which in itself could be problematic for a man - or, as Whyte suggests, a bully - so used to having things all his own way.

At this point, a loss would be disastrous and any notion of one day joining the list of British boxing greats all but dashed.

Whatever happens, win or lose, this bout is crucial and a coming of age showdown that each of the country’s most revered fighters have been forced to endure.

Five 'Coming of age' battles - won and lost... media Frank Bruno v Floyd Cummings (1983)

Many have compared Joshua’s astonishing power and musclebound physique to one of the most loved heavyweights in history.

Back in 1983, Frank Bruno was 18-0 with 18 knockouts and like Joshua, was being tipped for the top.

Enter American Floyd "Jumbo" Cummings, a robust bodybuilder with punching power to match.

Bruno was favourite after his effortless win streak but he had never encountered anything like Cummings before.

A hellacious shot connected with Bruno’s jaw at the end of the first round and the Londoner froze.

Hurt, stunned, and unsure what to do, the bell rescued his career. Slowly Bruno worked his way back, firing out his jab and drawing from reserves he never knew he had.

By the seventh round he was the winner, but the lessons from this encounter had to be repeated several times before he took heed, and claimed the WBC title in 1995. media Lennox Lewis v Gary Mason (1991)

Lennox Lewis would later become one of Bruno’s teachers along the way, but it was in 1991 when he passed his first real exam.

Back in the days when big fights took place midweek, and live on terrestrial television, British champion Gary Mason was unbeaten in 35 outings and highly ranked by several world sanctioning bodies.

The contest was scheduled for 12 rounds. The tenacious Mason tried with all his might to dent his opponent, but it was Lewis - ticking boxes as he went - who dished out the real punishment.

With Mason unable to see out of his swollen right eye, the contest was stopped.

To this day, Lewis, who went on to become one of the greatest of all-time, regularly mentions this bout as being vital in his development. media Audley Harrison v Danny Williams (2005)

For every Lewis, you’ll find an Audley Harrison. "A-Force" – like Lewis before him, and Joshua after – marched into the professional ranks clutching an Olympic gold medal and the hopes of a nation on his shoulders.

Gifted and seemingly on the brink of breaking into the world top 10, Harrison was a huge favourite to defeat the talented, but seemingly fading, Danny Williams in 2005.

But Williams - like Whyte - did not like his brash opponent, nor the hoopla that surrounded him.

What followed was a forgettable bout of indelible consequences. Harrison, gun shy, was exposed by a fighter desperate to win and lost a 12-round decision.

Audley, of course, would be given plenty of chances again. In hindsight, we discovered all we needed to know in this one. media David Haye v Carl Thompson (2004)

For Harrison, his defeat – and subsequent failures – would define his career. But for David Haye, his first loss simply added an extra layer.

In 2004, cruiserweight and amateur standout Haye was 10-0 (10) and, like Joshua, had feasted on some decent names who were long past their best.

Carl "The Cat" Thompson was also thought to be on the decline, and for the first four rounds of his clash with the young lion fought like a man whose best days were behind him.

Battered all over the ring, the veteran took a pounding but refused to fall and by the fifth session, Haye was exhausted.

The favourite, so used to rivals falling at his feet, made one last ditch attempt to bury his stubborn opponent, but the tables had already turned.

Thompson, a man who rarely went down without a fight, valiantly fired back and forced the stoppage.

The defeat haunted Haye but he would exorcise his demons as he went on to unify the world cruiserweight titles and become one of the best heavyweights of his era. media Ricky Hatton v Kosta Tszyu (2005)

Britain’s Ricky Hatton – who along with Haye became of one Britain’s greatest of the modern age – had to wait a little longer in his development to encounter a fight that showed the world what he was made of.

In 2002 he rose from the canvas to trump tough Irishman Eamonn Magee, but it was three years later when he had to dig the deepest.

Formidable light-welterweight leader Kostya Tszyu was considered one of the best fighters pound-for-pound and was widely thought to be too good for Hatton.

But the Mancunian legend turned in a performance of the ages that forever proved his worth, when he forced the IBF champion to quit on his stool after 11 gruelling rounds.

What followed was a rollercoaster, as Hatton ultimately found the likes of the great Floyd Mayweather and Manny Pacquiao too good in famous Las Vegas events.

For Hatton et al, it was the tests, the coming of age fights, which were so revealing. And for Joshua, his time to mature is now.

READ: The ascent of Conor McGregor - UFC's crossover superstar

READ: No evidence that Dillian Whyte can cope with Anthony Joshua's ferocious power

READ: Where's the value on the Joshua v Whyte undercard?

Anthony Joshua v Dillian Whyte betting