Vladyslav Sirenko Scores Stunning Last-Round Knockout of Otto Wallin

New York City, NY, USA - Vladyslav Sirenko produced the biggest victory of his career on Sunday night, knocking out former world title challenger Otto Wallin in the closing seconds of their ten-round heavyweight contest at the Infosys Theater at Madison Square Garden in New York City.

Sirenko, who improves to 23-1 (20 KOs), appeared to be heading toward the scorecards after a closely contested and largely tactical fight. Instead, the Ukrainian heavyweight found a devastating finish moments before the final bell, handing Wallin his first knockout defeat since his stoppage loss to Anthony Joshua in 2023. Wallin falls to 28-4 (16 KOs).

Sirenko Finds the Opening at the Last Possible Moment

Wallin attempted to control the contest from his southpaw stance, using his jab, movement and considerable experience to prevent Sirenko from consistently setting his feet.

Sirenko remained patient, however, applying pressure without recklessly charging into Wallin’s counters. The Ukrainian carried the greater single-shot threat, but Wallin’s awkward positioning and cautious approach kept the fight competitive through nine rounds.

With the contest almost over, Sirenko suddenly broke through.

A hard right hand disrupted Wallin’s balance before Sirenko followed with a powerful left hook that dropped the Swedish heavyweight heavily. The referee immediately ended the fight without beginning a count.

Early reports differ slightly over precisely how much time remained—one reported six seconds, while another described the knockout as occurring with only one second left—but all accounts agree that Sirenko secured the victory in the final moments of the tenth round.

It was an extraordinary conclusion to a fight that appeared certain to require the judges.

Wallin Taken to Hospital for Examination

Wallin received medical attention inside the ring before being removed on a stretcher and transported to Bellevue Hospital Center for precautionary examinations.

Wallin’s trainer, Travia Pierce, subsequently told Swedish media that the 35-year-old was “okay” and undergoing tests. It had not yet been determined whether Wallin would remain in hospital overnight.

The reassuring update was welcome after a concerning conclusion to the contest.

A Career-Changing Victory for Sirenko

The result dramatically changes the direction of Sirenko’s career.

Sirenko entered the bout attempting to recover his standing following a disappointing unanimous-decision loss to Solomon Dacres in July 2025. That defeat damaged the perception of a heavyweight who had previously built an impressive-looking unbeaten record but had yet to establish himself against recognized world-level opposition.

Wallin represented a significant step up.

Although the Swede had lost clearly to Joshua and Derek Chisora in recent years, he remained an experienced and technically capable heavyweight who had completed twelve rounds with Tyson Fury and defeated Murat Gassiev by split decision.

Sirenko has now accomplished something that Fury and Gassiev could not: he knocked Wallin out.

The Ukrainian still has questions to answer against the division’s leading contenders, but this was the kind of breakthrough performance he desperately needed. He maintained his composure through a difficult contest, remained dangerous until the final bell and ultimately delivered when the opportunity appeared.

Where Does Wallin Go From Here?

For Wallin, the defeat is a serious setback.

His careful, safety-first style has allowed him to remain competitive against a wide range of heavyweights, but it has also frequently left little margin for error. Wallin was only moments away from completing another competitive ten-round assignment when Sirenko abruptly ended the fight.

At 35, and now having lost three of his last five bouts, Wallin faces an uncertain road back toward the upper end of the heavyweight rankings.

His immediate health is the only important consideration following such a damaging knockout. Any discussion about his boxing future should wait until he has completed the necessary medical examinations and been given time to recover.

For Sirenko, however, the night represents a complete revival.

Written off by many following the Dacres defeat, Vladyslav Sirenko travelled to New York, faced the most accomplished opponent of his career and scored a dramatic tenth-round knockout at Madison Square Garden.