Jin Sasaki never stopped trying for the knockout, even as he ventured into uncharted territory.

The Ring's No. 9-rated welterweight instead had to settle for a lopsided twelve-round decision win over countryman Shoki Sakai. Scores were 118-110, 117-111 and 116-112 for Sasaki in their ESPN+/Lemino Pay-Per-View co-feature on Friday from Ariake Arena in Tokyo, Japan.

"He is a very tough fighter," Tokyo's Sasaki said of his opponent, as translated by Mizuka Koike.

Sasaki-Sakai served as the co-feature to the Naoya Inoue-Ye Joon Kim Ring/undisputed junior featherweight championship. It was the second straight time that Sasaki appeared on an Inoue undercard and he did not want to squander the opportunity.

The sweat formed on Sasaki's face during his stylish ring walk—complete with sunglasses and chaps—was all the evidenced needed that no warm-up period was required. The all-gas, no-brakes style was on display from the opening bell as he went right to work in hopes of racking up his seventh straight knockout.

Yokohama's Sakai provided an inviting target for the most part, but Sasaki's sloppy technique proved to be a detriment. His looping punches caused visible damage around Sakai's right eye but was also constantly left open for counter shots.

Still, Sakai struggled to defend against Sasaki's wide left hook and superior punching power. He suffered a cut early and swelling, but managed to punch his way back into the fight in the third. Sasaki never quite adjusted to Sakai's counter left hook or right uppercut.

It didn't matter on this night, as both fighters flashed dependable chins.

For Sasaki, it meant fighting past the eleventh round for the first time in his entertaining career.

The realization of going the distance crept up on the streaking contender in the later rounds, as he unloaded in a brutal eleventh round. Sakai smiled and nodded as he ate an overhand left.

Sasaki was far from done, however. He banged away at his opponent's midsection with thudding body shots throughout the contest and especially in the final six minutes. It set up booming right hands and left hooks upstairs but Sakai (29-15-13, 15 KOs) remained upright through the final bell.

The twelve-round distance win marked just the third time overall where Sasaki (19-1-1, 17 KOs) was forced to hear the scorecards. The only other occasions were in a four-round decision win in his sixth pro fight and then a July 2022 six-round draw.

Friday's win extended his current nine-fight unbeaten streak (8-0-1, 7 KOs) as he sits firmly in the top four among all the major sanctioning bodies. Sasaki sent a reminder in a language that all four major titlists—Jaron 'Boots' Ennis (33-0, 29 KOs; 1 No-Contest), Eimantas Stanionis (15-0, 9 KOs; 1 NC), Mario Barrios (29-2-1, 18 KOs) and Brian Norman Jr. (26-0, 20 KOs) can understand.

"I will become the first Japanese welterweight world champion," Sasaki vowed in his best English. "I'm absolutely confident that I'll win, so all you welterweight world champions, let's have the fight!

"Boots Ennis, Eimantas Stanionis, Brian Norman and Mario Barrios, I'm not going to run away or hide, I'm looking forward to the World title match this year!"

Jake Donovan is part of the U.S. team for The Ring. Follow Jake on X and Instagram.