Junto Nakatani battered Ryota Yamauchi throughout most of their one-sided, 112-pound title fight Saturday in Saitama, Japan.

The rangy southpaw, who is unusually tall for his division, hurt and stopped his countryman in the eighth round of their scheduled 12-rounder on the Gennadiy Golovkin-Ryota Murata undercard at Saitama Super Arena. The unbeaten, 24-year-old Nakatani (23-0, 18 KOs) made the second defense of his WBO flyweight title and became the first fighter to stop Yamauchi inside the distance (8-2, 7 KOs).

Tokyo’s Yamauchi, the WBO’s number two contender for Nakatani’s title, had won four straight fights before Sagamihara’s Nakatani stopped him. His only previous loss was a 12-round unanimous decision to Wulan Tuolehazi (then 10-3-1) in March 2019.

Yamauchi started the eighth round strong and appeared able to take Nakatani the distance by that point. A hard right by Yamauchi landed 25 seconds into the eighth round, but Nakatani took that shot well.

A straight left by Nakatani made Yamauchi take an awkward step with 50 seconds on the clock in the eighth round and indicated the end was near. Nakatani knew he could finish off Yamauchi with a flurry, and that’s exactly what he did.

An aggressive Nakatani unloaded various flush punches on Yamauchi during the first half of the seventh round.

Nakatani hit Yamauchi with an array of power punches during what amounted to a dominant sixth round. The champion kept his distance better in that round than he had done in the fifth round, which enabled him to open up on Yamauchi.

Yamauchi stayed in Nakatani’s chest throughout the fifth round, but Nakatani landed a lot of uppercuts in those three minutes. Yamauchi took Nakatani’s power better in that round than had been the case earlier in this fight.

Nakatani continued to pick apart Yamauchi during the fourth round, but Yamauchi showed a lot of toughness by coming forward during those three minutes.

Nakatani unloaded right uppercuts in the opening minute of the third round. Yamauchi bravely pressed forward, but he took a lot of punishment again in the third round.

A straight left and a right uppercut by Nakatani stopped Yamauchi in his tracks with just under 40 seconds on the clock in the third round.

Nakatani caught Yamauchi with another left hand that wobbled him about a minute into the second round. The champion continued to hammer Yamauchi with body and head shots – straight lefts and uppercuts mostly – during an entirely one-sided second round.

The marks and swelling on Yamauchi’s face reflected how hard the first two rounds were for him as the challenger walked back to his corner after the second round.

Nakatani nailed Yamauchi with a left hand that buckled his knees with 25 seconds to go in the first round and made the challenger hold him. Nakatani also drilled Yamauchi with a right uppercut before the first round ended.

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