As Joe Calzaghe finally ends his stellar 16-year undefeated professional career, we take a look at 10 of the greatest tests the Newbridge man faced in the ring.
Here is how he rose to the task on each occasion, maintaining his remarkable undefeated record and establishing himself as one of Britain's all-time great fighters.
In 1993 Calzaghe was close to turning professional, but decided to first target a third ABA title at a third weight class, hoping to become the first man to achieve that feat since Fred Webster in 1928.
Fighting at middleweight, Calzaghe was carrying the hand injury that would dog the rest of his career, but he managed to stop all his opponents on the way to the final.
There he found Darren Dorrington more resilient, the Bristolian taking three counts but going the distance.
Calzaghe was a clear winner in his last amateur fight, before turning professional in October with a first-round stoppage of Paul Hanlon on the undercard of Lennox Lewis v Frank Bruno at Cardiff Arms Park.
After three years as a professional, Calzaghe had won all 16 of his fights, had only gone beyond the fourth round twice, and only been taken the distance once.
But there was a distinct sense that he was thrown into the lions den for this, the first defence of his British title.
West Ham's Delaney was a talented 24-year-old who had won all 21 of his bouts.
To Calzaghe's chagrin, the Welshman's then-promoter Mickey Duff lost the purse bid, meaning the bout would take place on hostile territory, in Brentwood, Essex.
Two thousand fervent Delaney fans packed the International Centre, but their anti-Welsh jibes served to pump up Calzaghe.
After just 20 seconds Delaney was dropped for the first time in his career, and his nose was broken following a second first-round knock down.
The Englishman battled on, but was stopped after two more knock downs in the fifth round.
Eighteen months and five easy wins after Delaney, Calzaghe faced the fight he still considers his hardest.
The Welshman had been due to challenge Steve Collins for the WBO title, but his retirement meant former champion Chris Eubank stepped in to contest the vacant belt at the Sheffield Arena.
Eubank was past his best and struggled to make the weight at short notice, but the old warrior lived up to his promise to take the young challenger "into the trenches".
An adrenaline-fuelled Calzaghe made a spectacular start, a huge shot dropping his opponent in the first round for the first time in his life.
But the Welshman's inexperience meant he wasted too much energy in his early onslaught, Eubank rallying and forcing his foe to show champion qualities.
Calzaghe dug deep to go the 12 rounds for the first time in his career, and - despite a large points advantage - he was still trading blow-for-blow as the bell ended a simply spectacular fight.
Calzaghe's first five defences saw a sharp decline in the quality of his work, and after a controversial split-decision win over Robin Reid the points victories over Rick Thornberry and David Starie were two of the worst of his career.
While Calzaghe blamed an elbow problem that stopped his sparring and left his timing off, the Americans - ever mistrustful of European fighters - only saw a champion there for the taking.
Across the Atlantic, Omar Sheika was seen as the future of the super-middleweight division - and he was not shy of telling the world that he would "kill" the champion when they met at the Wembley Conference Centre.
But Calzaghe suddenly found himself injury free, a development he attributes to the fact that he gave up playing golf.
In training camp he was able to do his first sparring for a year, and quickly recovered his timing and form.
Sheika's comments wound up the Welshman, and he manhandled the challenger from the opening moments.
The American was blown away by a classy, physically dominant performance from Calzaghe, who wildly celebrated the relaunch of his career after the fifth-round stoppage.
Impressive defences against Richie Woodhall, Mario Veit and the hapless Will McIntyre maintained the interest of the US audience, paving the way for a big-money match-up against the former IBF champion from Philadelphia, Charles Brewer.
"He was a tremendous fighter," said Calzaghe. "He lost his title to Sven Ottke, but that was a bad decision and I know he came here convinced he would win."
Brewer - a converted southpaw who carried a very hard left - had a reputation as a brawler, and Calzaghe knew his best chance of winning was to box.
But the champion was caught to the body early on, and a combination of adrenaline and the fervent Cardiff International Arena crowd drew him into a toe-to-war war.
"I can rarely resist if my opponent is up for it," admits the Welshman.
Calzaghe was on top, but he was stunned by a superb Brewer combination in the seventh.
After being berated in the corner by father and trainer Enzo Calzaghe, the champion turned to his boxing skills for the rest of the fight to close out a comfortable points decision.
"It was one of my best fights and one of the most exciting for my fans," said Calzaghe.
A laboured win over Miguel Jimenez and a KO of the farcical Tocker Pudwill followed Brewer, and Calzaghe admitted to feeling "frustrated and complacent".
A second round straight out of Hollywood
US commentary on the fight
That was a dangerous combination, as next up at the Cardiff International Arena was the 'Slama from 'Bama, Byron Mitchell.
The former WBA champion arrived in Wales as very much a live contender - strong, in shape, and with huge power in both fists.
Again, Calzaghe's obvious path to victory was to box and move... but again the champion got caught up by the occasion and dragged into a slug-fest.
The Welshman tore into his foe in a spectacular opening, but while he landed with his wild, looping shots, Mitchell's less-showy work was straight, accurate and damaging.
The pattern continued in the second round as Mitchell caught his foe with three body shots and a short, hard right.
The champion spun round and dropped to the floor for the first time in his life, as a gasp preceded stunned silence in the CIA.
Calzaghe cleared his head and resolved to go straight back to war, evading Mitchell's killer blows before blasting him to the floor with a left hook.
The champion never gave his dangerous foe the chance to recover, leaping on him and forcing a stoppage with a furious attack, prompting one US commentator to describe "a second round straight out of Hollywood".
With the boxing world again at his feet after the Mitchell mauling, Calzaghe contrived to take it on his shin and see it dribble away.
A series of uninspiring opponents, renewed injury worries and a messy divorce led many to believe that the champion was over the hill and ready to be taken by the new US super-middleweight hope, Jeff Lacy.
The hype surrounding Lacy - the "mini Mike Tyson" - was infectious. "Ruthless", "devastating" and the "saviour of boxing" were some of the milder plaudits lauded on the St Petersburg man.
The pre-fight wisdom was that Calzaghe had to stay away from the challenger, to be wary of the power that had dismantled Reid and stopped 17 of 22 opponents.
Instead, he went straight into close-quarter combat, his hand speed allowing him to land furious clusters of punches while Lacy's increasingly scrambled brain was still getting his shoulder muscles into gear.
After 12 rounds of total dominance and supreme sporting skill, Lacy's own promoter Gary Shaw was screaming for the fight to be halted, and only a delay for loose tape on a glove saved the challenger from a stoppage.
Boxing legend Sugar Ray Leonard, who admitted to knowing little of Calzaghe before the fight, said: "Within two rounds I was a Calzaghe supporter, I stood up in front of the TV shouting, 'Wow, look at this guy'!.
"The performance he produced was amazing. It was Joe's great accomplishment, to reach that level, to scale that peak."
After uninspiring wins over Sakio Bika and Peter Manfredo Jr, the long-reigning champion took the toughest fight that was out there for him, a clash with the young, dangerous, undefeated WBA & WBC champion Kessler.
In front of 50,000 fans at Cardiff's Millennium Stadium, Calzaghe struggled with the giant Dane's solid technique and explosive power in the early exchanges.
But he dug deep to exploit his superior variety of boxing skills, sapping Kessler's strength with attacks to the body and closing out a unanimous points win.
"It doesn't get any bigger than that," said Calzaghe, who counts the fight as his most satisfying.
"[I was] fighting a younger man, I was an underdog and a lot of people thought that I was going to lose that one."
With the end of his career in sight, Calzaghe now only wanted the biggest fights and was determined to conquer the USA, stepping up to light-heavyweight for the Ring magazine's title.
Having sought a fight with 'The Executioner' Hopkins for years the showdown with the 43-year-old was finally delivered in the neon-glitz of Las Vegas in April 2008.
Hopkins' motor-mouth ensured a controversial build-up, and with Hollywood's glamorous greats thronging the Thomas & Mack Center it looked like the occasion had got to the boy from Newbridge.
Calzaghe was floored by a straight right in the opening exchanges, and Hopkins continued to do damage with clinical shots throughout the fight.
But Calzaghe did all the work in the fight, his work-rate forcing a heavy-breathing Hopkins to stall for time.
The Welshman's split-decision victory was seen as controversial by some, but - as ever - he had found a way to win.
Hopkins' stunning triumph over Kelly Pavlik later in the year gave added lustre to Calzaghe's victory, The Executioner showing that he was still a formidable operator at the highest level.
ROY JONES JR
Jones, acknowledged as the greatest fighter of the '90s, was another fighter Calzaghe had chased for years.
With Jones now aged 39 and past his best, the tables had turned and the Pensacola legend courted Calzaghe to a date at boxing's greatest venue, New York's Madison Square Garden.
Calzaghe again froze in the US spotlight, bludgeoned to the floor in the first round by a speedy right with a forearm follow through onto the bridge of his nose.
A strutting Jones felt he was back on top of the world, and in the early rounds the two fighters exchanged stinging blows of breathtaking speed.
True to form, Calzaghe turned to the unorthodox, dropping his hands and sticking his face between Jones' gloves, telling his foe he was too slow to touch him.
The Welshman was connecting with hurtful blows, fighting at a pace Jones could not sustain.
Calzaghe opened a horrific cut over Jones' eye in the seventh and coasted the rest of the way, throwing in a few Ali shuffles at boxing's spiritual home.
The bout looks like being Calzaghe's last, and the master-class was a fitting farewell.