IBF light heavyweight champion Artur Beterbiev (L) seized the WBC belt of Oleksandr Gvozdyk with a 10th-round technical knockout in Philadelphia

Philadelphia (AFP) - Artur Beterbiev unified boxing’s light heavyweight division on Friday with a 10th round stoppage of Oleksandr Gvozdyk in title clash between two undefeated boxers.

The 34-year-old Beterbiev knocked his Ukrainian opponent down three times in the 10th before referee Gary Rosato stopped it with 11 seconds left.

Beterbiev, who represented Russia in the 2008 and 2012 Olympics, defended his International Boxing Federation crown and seized Gvozdyk’s World Boxing Council belt.

Beterbiev, who trains in Montreal, Canada, improved to 15-0 with 15 knockouts and is the only major boxing champion to have knocked out all of his opponents.

Gvozdyk threw more punches, but Beterbiev landed the harder and more direct shots, mixing up his combinations by working the head and body in front of the crowd at The Liacouras Center in Philadelphia.

Beterbiev showed why he is considered one of boxing’s most devastating punchers in the final round.

Looking the fresher of the two, Beterbiev scored the first knockdown with a flicking left to the side of the face. He knocked him down again 30 seconds later and finished Gvozdyk off with an overhand right.

Gvozdyk had been warned by Rosato after the second knockdown that the fight would be stopped if there was one more and when he took a knee after absorbing the right, Rosato had no choice but to stop it.

Beterbiev was a slight underdog for the two-belt fight which marked the first time that two undefeated champions squared off in the light heavyweight division.

Gvozdyk, who suffered his first loss in 18 fights, was coming off a third round knockout of Doudou Ngumbu.

This was the second time the pair had clashed with Beterbiev also winning when they fought as amateurs 10 years ago. Beterbiev won that fight over a bloodied Gvozdyk by a second round stoppage.

Beterbiev’s next fight will be a mandatory defence against another undefeated fighter, China’s Meng Fanlong. Promoter Bob Arum wants to hold that fight early next year in China around the time of the Chinese New Year.

The fight was the first world title bout since American boxer Patrick Day died on Wednesday from brain injury suffered in a fight last weekend.

Day was honoured with a 10 bell salute prior to the main event.

The 27-year-old super welterweight from New York had undergone emergency brain surgery after being knocked out by Charles Conwell last Saturday at Chicago’s Wintrust Arena.

Day, who had been in a coma following the knockout, died surrounded by family and friends, his promoter said.

The American fighter had been carried unconscious from the ring on a stretcher on following his 10th round knockout.