Evander Holyfield is a fighter so obsessed with proving his doubters wrong, he still cannot walk away.
"The Real Deal" has competed at the top of the heavyweight division for over a decade, amassing four world titles by sheer force of will.
And despite two unsuccessful bids in the last three years and a battering at the hands of James Toney in October 2003, the 42-year-old Holyfield is determined to win a fifth.
Holyfield first came to the public's attention at the 1984 Olympic Games where he was favourite to win light heavyweight gold.l
However, he was disqualified in the semi-finals having knocked out opponent Kevin Barry after the referee called break.
Holyfield turned professional soon after and unified the cruiserweight division with an eighth-round knock-out of Carlos DeLeon in 1988.
Typically dogged in search of a new challenge, he immediately relinquished his belts and stepped up to the heavyweight ranks.
The "Real Deal" was written off by the boxing press, who argued the blown-up cruiserweight would struggle against the giants of the ring.
HOLYFIELD FACT FILE
Turned pro: 15/11/1984
Alias: The Real Deal
Height: 6ft 2in
Trainer: Don Turner
Promoter: Don King
But after just two years in the top division he defeated James "Buster" Douglas for the undisputed heavyweight crown in October 1990.
Holyfield was then scheduled to fight Mike Tyson, but the fight was postponed, first because of an injury to Tyson and then because of Tyson's conviction for rape.
He was champion for two years before losing a unanimous decision to the colossal Riddick Bowe in November 1992 - his first defeat in 29 professional fights.
Despite ending in defeat for Holyfield, the first Bowe fight illustrated the two qualities which above all made him a champion - determination and courage.
Few gave Holyfield much chance in the rematch, but he reclaimed the title with a 12-round decision the following year in another epic bout.
Holyfield was then stunned by Michael Moorer on another decision in 1994, and then knocked-out by Bowe, for the only time in his career, in a rubber match the following year.
The press considered him spent, but one fight later, Holyfield was challenging for and winning Tyson's crown, outclassing his foe in a brutal encounter to set up an infamous rematch.
Tyson, frustrated and behind on points, bit Holyfield's ear in the third round and was disqualified in one of boxing's most notorious encounters.
25/10/1990: KOs Buster Douglas to become undisputed heavyweight king
6/11/1993: Outpoints Riddick Bowe to reclaim the WBA and IBF titles
9/11/1996: KOs Mike Tyson to regain the WBA title for a third time
Holyfield took a big step toward unifying the division by knocking out Moorer in November 1997, but a new force in heavyweight boxing stood in his way.
Against WBC title holder Lennox Lewis in 1999, he was out-muscled and out-boxed for most of the 12 rounds, only for the judges to declare a draw before Lewis won the rematch on points.
He was seemingly out-fought by John Ruiz in 2000, only to be given another dubious decision, and thus he had regained the heavyweight title for a fourth time.
Holyfield lost a decision in the rematch, but still he refuses to go quietly.
Whether he can be ranked among the great heavyweights is a matter for debate.
Some point to the fact that in his four title-winning fights, three of his opponents were under-prepared or unmotivated and one was unlucky to lose on points.
In truth, as a natural cruiser fighting much of his career in the top division, he should go down as a great boxer, if not one a top tier heavyweight.
And when "The Real Deal" does finally walk into the sunset, he will be remembered as a fighter of astonishing bravery and desire, and as a champion of great dignity.