Krzysztof Glowacki turned a near-disastrous mixed martial arts debut into a highlight reel win.

The former two-time WBO cruiserweight titlist scored a sensational first-round knockout of Patryk Tolkaczewski as part of the KSW 83: Colosseum 2 MMA event Saturday at PGE Narodowy in Warsaw, Poland.

Tolkaczewski was in full mount and on the attack as Glowacki covered up while flat on his back to avoid further punishment. A stoppage loss seemed imminent for the former top boxing cruiserweight before he landed a single left hand to render his countryman unconscious.

Glowacki then rolled over and—from his knees—landed a follow-up left hand on a defenseless Tolkaczewski, also a former boxer. The fight was immediately halted at 1:33 of the opening round of their heavyweight contest, as Glowacki ran around the octagon in celebration.

The fight was the first of any kind for Glowacki since a fourth-round knockout loss to Richard Riakporhe on January 21 at AO Arena in Manchester, England. The 36-year-old Polish southpaw from Walcz announced his retirement from the ring in March but has since resurfaced in the octagon, where he is off to a 1-0 start.

Glowacki’s first WBO title reign began in similarly dramatic fashion. He recovered from a sixth-round knockdown to floor long-reigning titlist Marco Huck twice in the eleventh round to force a stoppage in their August 2015 slugfest that landed high among Fight of the Year lists. The knockout win for Glowacki left Huck unable to break the tie with Johnny Nelson for most successful cruiserweight title defenses in history.

Just one successful defense followed for Glowacki, where he scored four knockdowns en route to outpointing former champ Steve Cunningham over twelve rounds in April 2016. His reign ended with a loss later that September to Oleksandr Usyk (20-0, 13KOs), who went on to fully unify the division in 2018 before moving up to heavyweight the following year.

By that point, Glowacki claimed the interim WBO title and was upgraded to full titlist. His reign ended in a controversial third-round knockout to Mairis Briedis in June 2019, as the semifinal bout of the World Boxing Super Series cruiserweight tournament on the road in Riga, Latvia.

The poorly officiated contest served as grounds for a successful appeal filed by Glowacki with the WBO, who ordered an immediate rematch. Briedis was contractually bound to the WBSS tournament finale versus Yuniel Dorticos, which forced him to vacate.

Glowacki’s bid to become a three-time titlist ended with a one-sided sixth-round knockout loss to unbeaten Lawrence Okolie in March 2021. He sat out for more than a year before claiming a confidence-restoring knockout win last April 30 in his Walcz hometown before suffering a knockout loss to Riakporhe earlier this year before calling it a career.

Jake Donovan is a senior writer for Twitter: @JakeNDaBox