LAS VEGAS – Vincent Astrolabio’s ascent in the bantamweight division continued in impressive fashion Saturday night.

The Filipino contender knocked out Russia’s Nikolai Potapov in the sixth round of their IBF bantamweight elimination match at The Chelsea inside The Cosmopolitan of Las Vegas. Astrolabio (18-3, 13 KOs) dropped Potapov three times and became the first opponent to stop Potapov (23-3-1, 11 KOs) inside the distance in the opener of Showtime’s tripleheader.

Referee Robert Hoyle stopped their 12-round fight at 1:26 of the sixth round because Potapov didn’t reach his feet in time to beat Hoyle’s count.

Astrolabio secured a 118-pound title shot because he is now the IBF’s number one contender in the bantamweight division.

The 25-year-old Astrolabio’s victory over Potapov made him the IBF’s mandatory challenger for undefeated, fully unified bantamweight champion Naoya Inoue (24-0, 21 KOs). Potapov entered the ring ranked third among the IBF’s 118-pound contenders, three spots atop Astrolabio.

Japan’s Inoue might move up to the 122-pound division for his next fight. If Inoue gives up his IBF, WBA, WBC and WBO belts, Astrolabio could face second-ranked Emmanuel Rodriguez (21-2, 13 KOs, 1 NC), who lost the IBF belt to Inoue, for that title.

Astrolabio upset former two-division champion Guillermo Rigondeaux in his previous fight, a 10-rounder Astrolabio won by unanimous decision. The underdog dropped the Cuban southpaw in the eighth round, which was the difference on all three scorecards (95-94, 95-94, 95-94) on February 26 in Dubai.

Potapov, 32, had won three fights in a row after Joshua Greer Jr.’s controversial 12-round, majority-decision victory over him in July 2019 at Prudential Center in Newark, New Jersey.

It was evident in the sixth round Saturday night that Astrolabio’s power had taken its toll on Potapov. After a right hand by Astrolabio landed, Potapov took a knee, which accounted for Astrolabio’s third knockdown of their fight.

A battered Potapov didn’t attempt to beat Hoyle’s count.

Potapov’s left hook landed flush early in the fifth round. A right-left combination by Astrolabio made Potapov take a knee with just under 2:10 remaining in the fifth round, though.

Just before the fourth round ended, Astrolabio blasted Potapov with a right hand, but Potapov shook his head to indicate he wasn’t hurt by that punch.

Hoyle called for time just before the midway mark of the fourth round and warned both boxers for illegal tactics. About 30 seconds later, Hoyle stopped the action again and admonished Astrolabio for rabbit punches.

Potapov caught Astrolabio with a counter left hook that knocked him backward with 1:18 to go in the third round. Astrolabio drilled Potapov with a right hand several seconds after the third round began.

With under 30 seconds to go in the opening round, Astrolabio’s left hook appeared to graze Potapov, who went down. Potapov quickly got to his feet, but Hoyle called it a knockdown. Astrolabio continued to land the harder punches throughout the second round, when a cut opened around Potapov’s right eye.

Potapov went down 32 seconds into their bout, but Hoyle ruled that it wasn’t a knockdown, presumably because Astrolabio hit him behind his head.

Keith Idec is a senior writer/columnist for krikya360.com. He can be reached on Twitter @Idecboxing.