LAS VEGAS – It initially looked like Junto Nakatani would overwhelm Andrew Moloney with his size, strength, activity and accuracy very early in their fight Saturday night.

A determined Moloney almost made it all the way to the final bell, but Nakatani finally finished the tough Australian contender late in the last round of their 12-round, 115-pound championship match. A crushing left hand by the exceptional Japanese southpaw brutally knocked Moloney flat on his back with 20 seconds to go in their bout.

Referee Mark Nelson immediately waved an end to their one-sided title fight, in which Moloney was knocked down once apiece in the second, 11th and 12th rounds. The official time of the stoppage was 2:42 of the 12th round on the Devin Haney-Vasiliy Lomachenko undercard at MGM Grand Garden Arena.

The 25-year-old Nakatani won the WBO junior bantamweight title, which was vacant. Nakatani (25-0, 19 KOs), a former WBO flyweight titleholder, became a champion in a second weight class.

Moloney (25-3, 16 KOs) once owned the WBA interim super flyweight title, but he is 0-3 (1 NC) in championship matches over the past two years. His twin brother, Jason Moloney, fought through a fractured hand and beat the Philippines’ Vincent Astrolabio by majority decision to win the IBF bantamweight title a week earlier in Stockton, California.

In the round before Nakatani delivered a highlight-reel knockout, he drilled Moloney with a straight left that knocked Moloney to the seat of his trunks with 1:55 to go in the 11th round. Moloney commendably managed to make it to the end of that round, despite that he was dropped with nearly two minutes remaining in it.

A left-right combination by Nakatani appeared to affect Moloney with a little more than a minute on the clock in the ninth round. Moloney came back to throw hard punches of his own about 20 seconds later.

Moloney landed a right hand barely 50 seconds into the ninth round, but Nakatani kept throwing punches.

A left to the body by Nakatani landed late in the eighth round, when he followed up by attacking Moloney to his head. Nakatani landed a left hand from long range after the midway mark of the eighth round.

Nakatani and Moloney traded hard shots on the inside throughout an action-packed seventh round that was very competitive.

A right by Moloney landed with about 45 seconds to go in the sixth round. Moloney landed a hard right in an exchange a little more than a minute into the sixth round.

Moloney landed a flush right hand with just over a minute remaining in the fifth round, but Nakatani took it well. Back-to-back right uppercuts by Nakatani snapped back Moloney’s head barely a minute into the fifth round.

Moloney came forward and tried to work on the inside during the fourth round. Nakatani countered him with uppercuts a few times in the fourth round, but Nakatani didn’t have as much success in those three minutes as he did in each of the first three rounds.

Nakatani continued to catch Moloney with uppercuts after Nakatani suffered a nasty gash earlier in the third round.

After a strong second round in which he produced a knockdown, an accidental clash of heads caused a long cut between Nakatani’s eyes early in the third round.

Nelson called for a break in the action with 2:22 to go in the third round. A ringside physician examined his cut and quickly allowed the action to continue.

Nakatani caught Moloney with two left uppercuts before he cracked Moloney with a right uppercut that sent him to the canvas with 2:09 to go in the second round. Nakatani nailed Moloney with another right uppercut that got his attention toward the end of the second round.

Nakatani landed a hard left to Moloney’s body with just under 35 seconds to go in the first round. Moloney pressured Nakatani for most of the opening round, but he had trouble landing clean punches on the taller, rangier southpaw.

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