NEW YORK – Not even the toughest of light heavyweights could take Artur Beterbiev’s pulverizing power.

The unbeaten Beterbiev kept his perfect knockout record intact by dropping Joe Smith Jr. three times in less than two rounds and stopped him in the second round of their highly anticipated 175-pound title unification fight Saturday night. The Russian-born, Montreal-based Beterbiev (18-0, 18 KOs) dropped Smith once in the first round and twice in the second round, before Beterbiev wobbled Smith again and caused referee Harvey Dock to stop their brief fight.

The official time of the stoppage was 2:19 of the second round in the main event of a nine-bout card at Madison Square Garden’s Hulu Theater.

“Joe’s a little bit open and more easy for me to get him,” Beterbiev told ESPN’s Bernardo Osuna in the ring. “Two fighters both have good punch and both tried to get [there] first. This time I’m lucky – I get there first.”

Beterbiev, 37, retained his IBF and WBC light heavyweight titles and won the WBO belt from Smith. Beterbiev needs only the WBA crown owned by Dmitry Bivol (20-0, 11 KOs) to become boxing’s fully unified light heavyweight champion.

“Unification fights are more interesting, more motivating,” Beterbiev said. “I prefer unification fight. I want to be undisputed.”

The 32-year-old Smith (29-4, 22 KOs), of Mastic, New York, lost by technical knockout for just the second time in his 12-year pro career.

His only other TKO defeat was the consequence of a broken jaw in his seventh professional fight. Eddie Caminero broke Smith’s jaw in the second round of their August 2010 bout, but Smith fought until the fourth round, when he couldn’t withstand the extreme pain any longer.

After flooring Smith late in the first round, Beterbiev dropped Smith with another right hand 38 seconds into the second round. Like the first knockdown, Smith went down briefly to one knee and popped right back up to his feet.

A little more than a minute later, however, Beterbiev’s left hand knocked Smith into the ropes, which held him up and counted as a knockdown about 1:15 into the second round. Smith tried to fight out of the trouble, but he couldn’t withstand Beterbiev’s vaunted power.

Once Beterbiev wobbled Smith with a left uppercut, a right uppercut and a right that landed on the back of his head, Dock stepped between them and stopped the fight.

Beterbiev landed multiple right hands within the first 25 seconds of their fight. Smith took those shots well and landed a right hand of his own that made Beterbiev retreat during the middle minute of the opening round.

Smith slipped to the canvas with just over a minute to go in the first round. Just before the first round ended, however, Beterbiev caught Smith with a right hand that knocked him down to one knee.

Smith jumped right to his feet, but it was clear by then that he’d have difficulty dealing with Beterbiev’s precise punching, particularly his right hand.

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