Adonis Stevenson defeats Tommy Karpency, calls out Sergey Kovalev

Light heavyweight champion Adonis Stevenson's power never has been in question. It's just his recent run of opposition that repeatedly has drawn the ire of critics.

Both were on display Friday night, when Stevenson took on lightly regarded Tommy Karpency and defended his lineal title for the sixth time with an emphatic third-round TKO in the main event of a Premier Boxing Champions card at Toronto's Ricoh Coliseum.

Karpency (25-5-1, 14 KOs), a native of Adah, Pennsylvania, who scored an upset of former champion Chad Dawson last October, recently adopted the nickname of "Kryptonite" to combat Stevenson's "Superman" moniker. But Karpency was completely overmatched.

"I expected that," Stevenson said of the knockout. "[Karpency] tried. But the 'Kryptonite,' he lost today."

Stevenson (27-1, 22 KOs), 37, scored a pair of knockdowns and ran laps around the ring in celebration after referee Hector Afu waved off the fight at 21 seconds of Round 3 with Karpency in no shape to continue.

Karpency had his knees buckled on a Stevenson counter left hand in Round 1 and was dropped in the closing seconds of Round 2 by a left cross. He came out for the start of Round 3 on rubbery legs, and Stevenson made him pay by flooring him with a pair of hard left hands, leading to the stoppage.

After the fight, Stevenson, a native of Haiti who fights out of Quebec, continued his war of words with unbeaten unified titlist Sergey Kovalev, chastising him for pulling out of a WBC-mandated purse bid in April that greatly set back the chances of a fight between the two becoming a reality.

"Kovalev, you are easy work," Stevenson said. "Come on, you left the purse bid and disappeared, but it's time now that we unify the title and have unification fight."

Spence stops van Heerden

On the undercard Friday night, unbeaten welterweight Errol Spence Jr. took another big step in the transition from prospect to contender by scoring an eighth-round TKO against fellow southpaw Chris van Heerden.

Spence (18-0, 15 KOs), a native of Desoto, Texas, who is thought by many to be the next great welterweight, did nothing to disappoint. A 2012 U.S. Olympian, Spence outlanded van Heerden 153 to 69, according to CompuBox, and scored a pair of knockdowns in a dominant performance.

"It feels great," Spence said. "I wanted to have a spectacular, one-sided performance, and I think I did that."

Van Heerden (23-2-1, 12 KOs), a South African who fights out of Southern California, came forward throughout and did his best to get inside. But Spence, 25, was far too accurate and routinely made him pay with a stinging jab and combinations to the body.

Spence set the tone in Round 1 by turning van Heerden's face red with hard overhand lefts. Van Heerden, who lost a point for repeatedly spitting out his mouthpiece in Round 4, sported a pair of visibly swollen eyes by Round 5.

Van Heerden suffered the first knockdown of his career in Round 7 following an accumulation of damage. Spence dropped him a second time later in the round with a body shot.

Referee Allan Huggins stopped the fight at 50 seconds of Round 8 while Spence was landing one clean shot after another.

"I want the big fights and the big names, and I think I had to go out there and do this in order to get that," Spence said. "I want anybody in the Top 10. I feel like I deserve it. Put me in the rankings, because I want to fight the best."