Anthony Joshua has so much on his plate this weekend that he won't have wasted too much time dwelling on the historical implications of his rematch with Oleksandr Usyk.
The 32-year-old British heavyweight has not boxed since dropping a unanimous decision to the undefeated former undisputed cruiserweight champion, who took the IBF, WBA and WBO heavyweight titles from him in London last September.
Joshua has added decorated coach Robert Garcia to his team since that reverse and he will try to put new information and new tactics into operation to crack a puzzle he and Usyk's prior 18 professional opponents have found impossible.
If he pulls it all off, he will join an exclusive club. Having avenged his previous loss to Andy Ruiz Jr in 2019, another win in a heavyweight title fight would make Joshua a three-time world champion in boxing's glamour division.
The list of men to have accomplished that feat is a short one and it includes some of the finest heavyweights of all time.
Past boxers to be crowned three-time heavyweight champions
You can't keep more esteemed company than The Greatest. Ali upset the odds the first two times he won the title, befuddling the feared Sonny Liston in 1964 before perplexing George Foreman in Zaire with his rope-a-dope masterclass a decade later. After that contest and the Thriller in Manila against Joe Frazier, decline set in.
The 1976 light-heavyweight Olympic gold medallist Leon Spinks was a rookie professional when he outpointed Ali over 15 rounds in Las Vegas in 1978. Chastened, Ali knuckled down in camp and won a unanimous decision when they reconvened in New Orleans seven months later. On his last triumphant night he became the first three-time champion in history. It remains regrettable that it was not a final farewell.
With the greatest respect to Moorer, he probably does not belong in the historical company of the other men on this list and he remains best known for being the man a veteran Foreman knocked out to win back the title in 1994 at the age of 45. Nevertheless, his 1992 win over Bert Cooper for the then lightly-regarded WBO belt was an instant cult classic.
Both men were down and badly hurt in round one and, although Cooper decked Moorer in round three, the southpaw prevailed when he battered his man through the ropes in the fifth. Moorer's failure to defend the belt highlighted its lack of status at the time, but there was no doubting the pedigree of his shock win over Evander Holyfield for the IBF and WBA belts two years later when he climbed off the canvas to claim a majority decision.
Defeat to Foreman came immediately after but Moorer got his hands back on the IBF belt by beating Axel Schulz on a split decision in June 1996. He defended it by taking unbeaten records from Frans Botha and Vaughn Bean before being knocked down five times in a punishing rematch with Holyfield.
Holyfield's revenge win against Moorer continued his own third reign and was his first fight since Mike Tyson gorged on his ears. A former cruiserweight champion like Usyk, Holyfield is in Jeddah this week and remains the only four-time world heavyweight champion thanks to a dogged win over John Ruiz for the vacant WBA belt in August 2000, one of the belts he lost after a draw and a loss in his unification double-header in 1999 with Lennox Lewis.
His first run as champion came when he brought James ‘Buster’ Douglas back down to earth following his seismic upset of Tyson. He caught up the IBF, WBA and WBC crowns in the first of his three-fight series with Riddick Bowe, whom he edged via majority decision in their rematch before losing the first fight with Moorer.
Holyfield tried to become a five-time champion but drew a rubber match with Ruiz after losing their return encounter. He then dropped a unanimous decision to IBF champion Chris Byrd.
Lewis' performances against Holyfield were arguably the finest of his career but did not begin a championship reign as he already held the WBC belt at the time. He lifted that for a second occasion thanks to a revenge victory over Oliver McCall in 1997, two and a half years after being stunned by the volatile but destructive American at Wembley Arena.
Bowe's refusal to face Lewis meant he was crowned champion after knocking out Donovan 'Razor' Ruddock in a final eliminator. His third stint as champion arrived in far more satisfying fashion as he brutally knocked out Hasim Rahman in an immediate rematch following a shock 2003 defeat in South Africa. That meant Lewis finally got his hands on Tyson for a dominant triumph and he walked away after Vitali Klitschko, resisting lucrative overtures for a return.
The elder Klitschko's presence on this list is different to the others in that it lacks dramatic redemption arcs. A three-fight run as WBO champion ended in 1999 with Klitschko clearly up on the cards against Byrd when he withdraw due to a shoulder injury. The American was on the wrong end of a landslide defeat to Wladimir Klitschko, who decked him twice, in his next fight.
Vitali's next shot came against Lewis, who stopped him on cuts in a 2003 thriller in Los Angeles. Klitschko would fight 13 times more as a pro and won them all. He knocked out Corrie Sanders, who had blitzed Wladimir inside two round in his previous bout, to win the vacant WBC title that he defended against Britain's Danny Williams.
Klitschko suffered a cruciate knee ligament injury in the build-up to his next defence against Rahman. He retired and was declared 'champion emeritus' by the WBC, meaning he was able to immediately fight and beat WBC belt holder Samuel Peter after a four-year absence in October 2008.