CARSON, Calif. – Subriel Matias has stormed into title contention.

The merciless punching Puerto Rican picked up the biggest victory of his career, forcing Kazakhstan’s Batyrzhan Jukembayev to quit on his stool after eight brutal rounds in their IBF junior welterweight title eliminator. Matias scored a knockdown in round four and weathered several momentum shifts to force the stoppage in between rounds eight and nine Saturday evening at Dignity Health Sports Park in Carson, California.

Action rarely strayed from the center of the ring, with the pair of junior welterweight punchers fighting at close quarters. Matias was trying to set up his right hand but overcommitted on his wind up as Jukembayev cracked the Boricua with a straight left hand. Matias took the shot well but was being outworked and beaten to the punch on the inside.

Jukembayev connected with a sizzling right hook to begin round three. Matias looked to counter but was unable to shoot his left hook past Jukembayev’s textbook defense. The Puerto Rican contender finally found his opening late in the round, landing a right hand and letting his hands go in the closing seconds.

The round-ending sequence proved to be a momentum shift for Matias who went on the attack in round four. Jukembayev’s guard was down just enough for Matias to crack him with a right hand and left hook to provide the bout’s lone knockdown. Jukembayev not only beat the count but rallied back to stun Matias late in the round to draw a rise out of the passionate crowd.

Jukembayev looked to turn the tide in his favor in round five while contending with a cut high on his skull, only for Matias to reclaim control. A left hook left Jukembayev briefly dazed and cornered midway through the round. The Kazakh southpaw came back to land a right hook upstairs, only for Matias to come storming back and land flush right hands.

Matias rocked Jukembayev with a left hook late in a high octane round six. Jukembayev was slowing down as Matias continued to pick up steam, offering a right hand-heavy finish to the round.

Matias was in a groove for much of round seven, sensing something big. It would come, only in the wrong direction as Jukembayev rallied back to slam home a right hook across Matias’ chin. Jukembayev moved in to follow up, with Matias shaking off the shot to land a right hand as the two traded through the remainder of the round.

The pivotal moment provided Jukembayev with a spark as round seven began. Matias still had plenty of fight left in him, absorbing the incoming to press forward with right hands up top and left hooks to the body. Matias continued to press the action in round eight, landing a steady stream of power shots.

It proved to be too much for Jukembayev to handle as his corner informed referee Ray Corona that he was unable to continue. The heartbreaking moment leaves Jukembayev with his first loss as he falls to 18-1 (14KOs).

Matias picks up his second straight high profile knockout on Showtime, as he improves to 17-1 (17KOs). The prolific knockout artist is now in position to eventually challenge for the IBF junior welterweight title held by undisputed champion Josh Taylor, though he will have to wait out another eliminator between Jeremias Ponce and Lewis Ritson.

Matias-Jukembayev served as the chief support of a Showtime tripleheader. Headlining the show, Nordine Oubaali (17-0, 12KOs) defends his WBC bantamweight title versus former four-division champ Nonito Donaire (40-6, 26KOs).

Jake Donovan is a senior writer for Twitter: @JakeNDaBox