Naoya Inoue is the best fighter in the world -- and an all-time great

Naoya Inoue, left, demolished Stephen Fulton in an eighth-round TKO victory to win the WBC and WBO junior featherweight titles. Naoki Fukuda

Naoya Inoue isn't simply the best boxer in the world -- he's an all-time great still adding chapters to his legendary career.

"The Monster" continued his climb up the mythical all-time list with yet another see-it-to-believe-it performance, a pulverizing eighth-round TKO of Stephen Fulton on Tuesday in Tokyo to capture the WBC and WBO junior featherweight titles.

The Japanese star didn't just deliver a beatdown with his otherworldly speed and power; he also outboxed Fulton in dominant fashion by clearly winning every round until the stoppage.

By Round 8, Fulton was bloody and on the receiving end of a one-sided demolition when Inoue unleashed a brutal right hand that sent Fulton reeling. It appeared he was going down when Inoue crashed a left hook into his face that ensured Fulton's body hit the canvas.

Fulton somehow got up but was in no shape to continue when Inoue (25-0, 22 KOs) was suddenly in his face, delivering a flurry that folded him into a heap as the ref saved him from further punishment.

There can be no doubt that Inoue is the pound-for-pound king, and with this scintillating performance, he served notice to Errol Spence Jr. and Terence Crawford. They meet for the undisputed welterweight championship on Saturday in Las Vegas, and the promotion has been billed as a battle for pound-for-pound supremacy.

But if either fighter truly hopes to unseat Inoue, he will have to come through with something extraordinary Saturday. In all likelihood, they'll be competing for the No. 2 spot behind Inoue.

The top position in the pound-for-pound rankings belongs to Inoue, who easily dispatched the No. 1 boxer at 122 pounds in his first fight at the weight class. There's no one else in boxing right now who's accomplishing what Inoue is doing.

The 30-year-old won his first title at 108 pounds and has more than carried his power four weight classes north.

Fulton, a very good fighter in his own right and who became a champion in 2021 by defeating Brandon Figueroa, appeared clueless on how to handle Inoue. Outside of two chopping right hands Fulton landed flush in Round 7, there were only a handful of other shots of consequence by him throughout the bout.

Inoue can do it all. His footwork is outstanding, allowing him to set up shots from uncanny angles. His hand speed is unmatched, which made Fulton hesitant to open up for fear of counter shots. And Inoue's punches are sharp and compact, allowing little margin for error from his foes.

Inoue, who's 5-foot-5, said leading into the fight that he was "pushing the boundaries of my build, my limits," but so far, that hasn't come close to being true. Inoue's talent doesn't seem constrained by weight classes. The truly great fighters aren't tested until they move up so far in weight that it's simply too much.

Perhaps at some point, that will be the case for Inoue. But not yet. He welcomed Marlon Tapales -- who holds the other two titles at junior featherweight -- into the ring afterward, setting up a showdown for the undisputed 122-pound championship later this year.

Inoue will be a heavy favorite to capture all four belts at a second weight class after he won the undisputed bantamweight championship with an 11th-round KO of Paul Butler in December.

After Tapales, maybe Inoue will be done with 122 pounds, too. With his awesome power still present at 122, it stands to reason that he can clean out 126 pounds, too.

Robeisy Ramirez, an Olympic gold medalist, retained his featherweight title with a fifth-round TKO in the chief support bout Tuesday. That's a natural fight for Inoue next year.

The question now becomes: How far can Inoue go up in weight? When will it be too much?

In the style of the great Manny Pacquiao, who also won his first title at 108 pounds, perhaps Inoue can also perform at an elite level at 130 and beyond. With everything Inoue has accomplished so far, it would be foolish to ever doubt him.