After the WBO gained recognition in the early 2000s -- kicking off boxing's four-belt era -- it became that much more difficult to earn status as an undisputed champion.
Even when a fighter can collect all four major world titles, as Josh Taylor did nearly two years ago when he defeated Jose Ramirez, it's often more challenging to keep them together -- and that's even before boxers step inside the ropes.
Taylor defeated Jack Catterall last year, albeit in controversial fashion, but was stripped of three of his four titles anyway as he pushed for the rematch instead of fulfilling the mandatory obligations that would ultimately impede the second fight with Catterall.
Following an injury, Taylor is set to defend his lone title, the WBO junior welterweight belt, against former unified lightweight champion Teofimo Lopez Jr. on June 10 at New York's Madison Square Garden (ESPN and ESPN+). The other three titles he once held? Splintered amongst three different boxers.
Boxing lost another undisputed champion in Naoya Inoue when the Japanese star announced he would vacate his four 118-pound titles to move up to 122 pounds for a shot at unified champion Stephen Fulton.
Now, three undisputed champions remain in men's boxing: Canelo Alvarez, Jermell Charlo and Devin Haney.
Canelo meets John Ryder on May 6 in Jalisco, Mexico -- his first fight south of the border in 10 years -- and all four super middleweight titles will be on the line. Alvarez long aspired to become undisputed and accomplished the feat with a TKO victory over Caleb Plant in 2021.
The winner of the March 25 bout between Plant and David Benavidez could be in line for a future shot at Alvarez, especially if it's Benavidez.
Charlo was scheduled to defend his undisputed junior middleweight championship against Tim Tszyu on Jan. 28, but a hand injury postponed the bout. Rather than wait around, Tszyu took on his toughest opponent yet, former champion Tony Harrison, and delivered an impressive performance with a ninth-round TKO victory on Feb. 11 in Australia.
Charlo and Tszyu are expected to meet in the rescheduled bout for all four 154-pound belts later this year.
Finally, there's Haney, who won the undisputed lightweight championship with a rout of George Kambosos Jr. last year in Australia. The American kept all four 135-pound belts with an even-more decisive victory in the October rematch, also Down Under. Haney is set to take on his toughest test yet, a May 20 bout against Vasiliy Lomachenko in Las Vegas on ESPN PPV, where lightweight supremacy will be determined.
Soon enough, others could join that trio in the undisputed ranks. Four divisions are only one fight away from crowning an undisputed champion. Let's take a look at those potential matchups:
Heavyweight: Tyson Fury vs. Oleksandr Usyk
Of the four matchups, this could be the only one to happen in 2023. The sides agreed on a 70/30 purse split in favor of "The Gypsy King" for an undisputed heavyweight championship bout planned for April 29 at London's Wembley Stadium.
Fury and Usyk have continued to trade barbs on social media recently, and though contracts aren't yet signed, the bout appears to be a go barring an 11th-hour collapse.
The matchup will crown boxing's first undisputed heavyweight champion in the four-belt era, and the sport's first such champ since Lennox Lewis reigned supreme in the early 2000s. (Fury holds the WBC title, while Usyk has the WBA, IBF and WBO belts he won from Anthony Joshua.) It's also a fascinating style clash between two future Hall of Famers at the top of their games.
Fury and Usyk are No. 1 and 2, respectively, in ESPN's heavyweight rankings, but they're also two of the best fighters in the world regardless of weight. Usyk is No. 3 on ESPN's pound-for-pound list, with Fury four spots behind him.
And with a win, Usyk would become undisputed in his second division after the Ukrainian collected all four cruiserweight belts in 2018 (to go along with an Olympic gold medal in 2012).
With four mandatory defenses looming -- led by Daniel Dubois and the WBA -- whoever emerges with the belts isn't likely to be undisputed for long, even if he'll still be the lineal champion.
Light heavyweight: Artur Beterbiev vs. Dmitry Bivol
This matchup was in talks to take place in Russia last spring before Bivol won the Canelo sweepstakes. Following Bivol's lopsided upset victory over Alvarez, a fight between Beterbiev, the WBC, WBO and IBF champion, and IBF titlist Bivol is bigger than ever. But it won't happen next.
The Russian-Canadian fulfilled his WBO obligation in January with an eighth-round TKO victory over Anthony Yarde, in a furious action fight, but last week, the WBC ordered Beterbiev to defend his title against former super middleweight champion Callum Smith. Bivol has defended his WBA belt nine times, including twice in 2022, the rout of Alvarez in May and against Zurdo Ramirez in November.
Beterbiev, 38, is boxing's only champion with a 100% knockout ratio, but against Bivol, he might be counted as an underdog for the first time. Russia's Bivol is ESPN's top light heavyweight, while Beterbiev is No. 2 (Bivol, at No. 6, is two spots ahead of Beterbiev on the pound-for-pound list).
Bivol may meet Alvarez in a September rematch, this time at 168 pounds for the undisputed super middleweight championship. Although it appears increasingly likely we'll have to wait until 2023 for this appetizing matchup, if it happens at all.
Welterweight: Errol Spence Jr. vs. Terence Crawford
Ah yes, Spence and Crawford, who have been on a collision course for years and years at this juncture. The two best 147-pounders in the world were on the precipice of a deal for a fight last November, but talks collapsed in the late stages.
Spence is poised to move up to 154 pounds for a summer meeting against Keith Thurman. The WBA ruled that Spence will have 30 days after the fight to either close a deal to fight Crawford for the undisputed championship, or face the winner of the April 29 bout between WBA "regular" welterweight titlist, Eimantas Stanionis and Vergil Ortiz.
It's possible that Spence never returns to 147 pounds, but he has talked to Crawford in recent weeks about making the long-awaited fight happen. Spence also holds the WBC and IBF titles at 147 pounds. His championship résumé includes victories over Mikey Garcia, Shawn Porter and Danny Garcia.
Crawford, meanwhile, is in talks for a bout against Alexis Rocha after the WBO ordered the mandatory bout last month. Crawford is ESPN's top welterweight and No. 1 pound-for-pound boxer. Spence is No. 2 at 147 pounds and No. 4 pound-for-pound.
There remains hope Spence-Crawford will one day materialize, but undisputed status at 147 pounds eludes the fans for now.
Junior featherweight: Stephen Fulton/Naoya Inoue vs. Murodjon Akhmadaliev
Fulton will travel to Japan for a megafight against Inoue on May 7 in Yokohama (Sunday morning on ESPN+) and the Philadelphian will have his WBC and WBO belts on the line in a high-stakes matchup that is among the best the sport can deliver.
Inoue is a former bantamweight undisputed champion and has won titles in three different divisions. He is rated No. 2 by ESPN on the pound-for-pound rankings and will test his greatness against a bigger, stronger fighter who also happens to be a battle-tested elite boxer. Fulton often throws upward of 1,000 punches and can fight both inside and outside.
Whoever wins won't just cement himself as one of the sport's top pound-for-pound fighters -- he'll be only one fight away from being undisputed at 122 pounds. Uzbekistan's Akhmadaliev, an Olympic bronze medalist, has the WBA and IBF titles at junior featherweight.
Akhmadaliev, ESPN's No. 2 junior featherweight (behind Fulton) will defend his belts against Marlon Tapales on April 8 in San Antonio. Akhmadaliev will be heavily favored to retain them, and then wait to see what happens on May 7 in Japan. With no other natural matchup for Akhmadaliev on the horizon, a fight against the winner of Fulton-Inoue could happen later this year, particularly if it's Inoue, a major money generator in Japan who promises career-high paydays for opponents.