One of the most interesting fights on the boxing calendar has been postponed.

BoxingScene.com has confirmed that Japanese superstar Naoya Inoue has suffered an undisclosed injury during training camp that has forced the three-division champion to withdraw from his 122-pound title fight against Stephen Fulton Jr. Inoue, who became boxing’s fully unified bantamweight champion three months ago, moved up to the junior featherweight division to challenge Fulton for his WBC and WBO 122-pound crowns May 7 at Yokohama Arena in Yokohama, Japan, Inoue’s hometown.

Philadelphia’s Fulton confirmed through his Twitter account Tuesday that their fight will be rescheduled.

ESPN.com’s Mike Coppinger, who first reported that Inoue’s injury caused a postponement, reported Tuesday that Fulton-Inoue will be rescheduled for some point this summer.

The 29-year-old Inoue (24-0, 21 KOs) is commonly considered one of the top three fighters, pound-for-pound, in boxing. His 11th-round knockout of England’s Paul Butler (34-3, 15 KOs) on December 13 made him boxing’s first undisputed 118-pound champion of the four-belt era.

The 28-year-old Fulton (21-0, 8 KOs) will be forced to extend his layoff to over one year while waiting for Inoue to recover from his injury. Fulton’s most recent bout took place last June 4, when he easily out-boxed ex-WBA 122-pound champ Daniel Roman (29-4-1, 10 KOs) on his way to winning a 12-round unanimous decision at The Armory in Minneapolis.

Fulton considered moving up to the featherweight limit of 126 pounds for a rematch with Brandon Figueroa after he defeated Roman. Once the Inoue bout became a realistic possibility, however, Fulton informed Premier Boxing Champions founder Al Haymon that he wanted this career-defining fight against Inoue more than a rematch with Figueroa.

Fulton defeated Figueroa (24-1-1, 18 KOs) by majority decision in their fan-friendly, 12-round, 122-pound title unification fight in November 2021 at Park MGM’s Dolby Live in Las Vegas.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.