Artur Beterbiev’s concussive power was too much for even a durable challenger who had never been down as an amateur or professional before they fought Saturday night.

The ruthless Russian knockout artist overpowered England’s Callum Smith, dropped him twice during the seventh round and caused Smith’s trainer, Buddy McGirt, to stop their 12-round fight for Beterbiev’s three light heavyweight titles in Quebec City, Canada. McGirt entered the ring to get referee Mike Griffin to end their fight exactly two minutes into the seventh round.

Beterbiev brutalized the strong, skilled Smith, who had difficulty fending off the aggressive, heavy-handed Beterbiev in a noticeably tiny ring throughout a main event ESPN televised from Videotron Centre.

Montreal’s Beterbiev, 38, kept his perfect record intact (20-0, 20 KOs), became the first fighter to knock out Smith (29-2, 21 KOs) and retained his IBF, WBC and WBO light heavyweight titles. He also denied Liverpool’s Smith, 33, in the former WBA super middleweight title-holder’s attempt to become a world champion in a second division.

“You know, we always have a couple strategies,” Beterbiev told ESPN’s Bernardo Osuna in the ring. “We always do not only one, you know? You need to be prepared for several strategies. And he gave me [a] good fight, you know? He stayed strong, he good. Thank you [to] him, but you know, today luck is on my side.”

Beterbiev then emphasized that he wants to finally fight WBA champ Dmitry Bivol next in a long-awaited showdown that would crown the first undisputed light heavyweight champion of boxing’s four-belt era.

Before Saturday night, Smith had lost only a 12-round unanimous decision to undisputed super middleweight champ Canelo Alvarez (60-2-2, 39 KOs) in December 2020 at Alamodome in San Antonio.

Smith seemed to begin fading early in the seventh round.

Beterbiev landed a right that made Smith stumble a little less than a minute into the seventh round. Several more punishing punches from Beterbiev sent Smith to the canvas for the first time in his career with just over 1:50 to go in the seventh round.

Smith made it to his feet, but Beterbiev overwhelmed him with an onslaught of damaging shots that knocked Smith down again. A diminished Smith made it to his feet again, but McGirt had already entered the ring to stop the bout.

Smith’s hard left to Beterbiev’s body landed with just over 1:40 to go in the sixth round. Beterbiev stung Smith with a right hand that landed a little less than 20 seconds into the sixth round.

Smith landed a hard left to Beterbiev’s body with just under a minute to go in the fifth round. A right up top by Smith landed about 10 seconds later.

Smith bled from his nose, however, as he walked back to his corner following the fifth round.

Smith landed back-to-back left hooks as the fourth round wound down.

A right uppercut by Smith landed with just under a minute remaining in the fourth round. An assertive Beterbiev landed numerous power punches that made Smith hold him during the middle minute of the fourth round.

Beterbiev and Smith traded left hooks a little less than a minute into the fourth round. Smith landed a left hook in an exchange about 30 seconds into the fourth round.

A chopping right hand by Beterbiev followed a right uppercut that connected toward the end of the third round. Beterbiev continued landing his jab with just over a minute on the clock in the third round.

Griffin warned Smith for a low blow with about 1:50 to go in the third round. A hard jab by Beterbiev landed 45 seconds into the third round.

Smith connected with several jabs in the final minute of the second round, but Beterbiev snapped his head back with a stiff jab of his own soon thereafter.

Beterbiev blasted Smith with a thudding right to his body just before the midway mark of the second round. A short right over the top of Smith’s jab landed barely 35 seconds into the second round.

Beterbiev landed a right hand around Smith’s guard with just under 20 seconds to go in the first round.

A right and a left by Smith backed up Beterbiev with a little less than a minute to go in the opening round. Beterbiev smothered Smith as soon as their fight started because he didn’t want Smith to get good extension on his punches.

Smith and Beterbiev both ended long layoffs Saturday night.

Smith last fought in August 2022, when he knocked out France’s Mathieu Bauderlique (21-2, 12 KOs) in the fourth round of their fight at Jeddah Superdome in Jeddah, Saudi Arabia. Beterbiev’s previous appearance took place last January 28, the night he stopped England’s Anthony Yarde (24-3, 23 KOs) in the eighth round at OVO Arena Wembley in London.

Beterbiev and Smith were supposed to square off August 19, but their bout was postponed almost five months because Beterbiev developed an infection in his jaw that forced him to stop training late in July.

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