Japan's Naoya Inoue said he was still as hungry as ever after becoming an undisputed world champion in a second weight class on Tuesday, knocking out Marlon Tapales to claim all four super-bantamweight belts.

The unbeaten Inoue, nicknamed "Monster", floored the Philippines fighter with a huge right hand in the 10th round in Tokyo to add the WBA and IBF titles to his own WBC and WBO belts.

He became only the second man to unify all four world titles in two different weight classes, following American Terence Crawford.

Inoue needed just two fights to become the first-ever undisputed super-bantamweight world champion, 12 months after completing his rampage through the bantamweight division.

The 30-year-old took his record to 26-0 with 23 KOs and said he was just getting started at the higher weight class.

"One year ago, I was in a similar situation after claiming all four belts," said Inoue, who last year became the first undisputed bantamweight champion in half a century before vacating his titles to move up a division.

"I wanted to show my appreciation to all the people who had supported my career.

"But regardless of the fact that I have these four belts, I still want to fight more great matches."

Inoue knocked out American Stephen Crawford in his super-bantamweight debut in July but he had to dig deeper to see off Tapales.

The 31-year-old from the Philippines went down in the fourth round but clawed his way back into the match with a dogged performance.

Inoue finally ended Tapales's challenge with a ferocious right hand that his opponent never looked like getting up from.

Inoue said Tapales was a "very tough" fighter who surprised him with his strong defence.

"He kept a poker face throughout and didn't show that my punches were doing him any damage, so I was quite surprised when he went down in the tenth round," he said.

'Sense of achievement' 

Tapales upset Uzbekistan's Murodjon Akhmadaliev by split decision in April to win the IBF and WBA titles.

He vowed to come back from the loss but conceded that the result was a fair one.

"I was impressed by Inoue's technique as a boxer, and I was surprised by his speed," said Tapales, whose record dropped to 37-4 with 19 KOs.

"He was very fast and I just wasn't able to catch up with him."

Inoue has won world titles in four different weight divisions, having also triumphed at the light-flyweight and super-flyweight levels.

He knocked out England's Paul Butler in December last year to become the first undisputed bantamweight world champion since Panama's Enrique Pinder in 1972.

Crawford beat fellow American Errol Spence in July to win all the welterweight belts and become the first man to unify all four world titles in two different weight classes.

Inoue said he felt "a sense of achievement" after following in Crawford's footsteps.

"I think super-bantamweight is the most suitable weight class for me at the moment," Inoue said.

"Next year and the year after that, I want to prove that I can become an even stronger fighter."

Inoue has said that he intends to retire at 35 but he hinted earlier this year that he might prolong his career for two extra years.

He said his performances will dictate when he hangs up his gloves.

"If I feel like I'm slowing down, I might even retire before I'm 35," he said.

"But I don't want to talk about retirement just now."