Mariusz Joniak vs Karol Durszlewicz – Anticipation Builds Ahead of KSW XTB 115!

On February 21, 2026, the city of Lubin will once again become the center of Polish MMA emotions. The XTB KSW 115 gala, held at the RCS Arena, promises a night full of high-level fights, adrenaline, and unforgettable moments. Among the many exciting matchups, one bout stands out in particular – the clash between Mariusz Joniak and our brand ambassador Karol Durszlewicz.

This fight is a classic confrontation of experience versus youth, where a seasoned veteran of the cage will face an undefeated, hungry prospect who is just beginning to make his mark in the KSW organization. Below, we take a closer look at both fighters to help fans better understand why this matchup is one of the most intriguing on the card and why it is worth supporting Karol Durszlewicz, an ambassador of Środowisko Miejskie.

🥋 Mariusz Joniak – The Experienced Cage Veteran

Record: 12-6-0 (2 KO, 8 Submissions)
Weight class: Bantamweight (61.2 kg)
KSW ranking: #9 in the bantamweight division

Mariusz Joniak is widely recognized as a high-level grappler and one of the more experienced fighters in the Polish MMA scene. He began his professional career in 2016 and has since competed in 18 professional bouts, collecting victories through both submissions and ground-and-pound finishes.

A black belt in Brazilian Jiu-Jitsu, Joniak has built his reputation primarily on his exceptional ground game. Out of his twelve career wins, eight came via submission, highlighting his technical proficiency, control, and composure on the mat. His style is calculated and methodical, often wearing opponents down before capitalizing on mistakes in grappling exchanges.

Joniak has spent the last few years competing regularly inside the KSW cage, facing a variety of strong and well-rounded opponents. His most recent appearance came at KSW 98, where he fought Islam Djabrailov but lost via decision. Prior to that, he secured notable wins over fighters such as Sebastian Romanowski and Tobiasz Le, proving that he can compete at a high level within Europe’s leading MMA organization.

Although known mainly for his ground skills, Joniak is by no means one-dimensional. He possesses solid striking fundamentals and the ability to finish fights on the feet when opportunities arise. This versatility makes him a dangerous opponent for any fighter who underestimates his experience and composure.

💥 Karol Durszlewicz – An Undefeated Prospect with Explosive Potential

Record: 4-0-0 (2 KO, 1 Submission, 1 Decision)
Weight class: Bantamweight
Gym: Fight Team MMA Brodnica

Karol Durszlewicz is one of the most exciting young talents currently emerging in Polish MMA. Despite having only recently turned professional, he has already compiled a perfect undefeated record, demonstrating maturity and confidence beyond his years.

Out of his four professional wins, three were finished before the final bell, showcasing his finishing instinct and offensive mindset. One of his most impressive performances came at KSW 108, where he defeated Grzegorz Stabach with a devastating first-round body-shot knockout. That fight clearly highlighted his power, timing, and killer instinct inside the cage.

Before entering the professional ranks, Durszlewicz built a strong foundation as an amateur fighter. He amassed close to 30 amateur victories, collected numerous medals, and earned a bronze medal at the 2022 IMMAF European Championships, gaining valuable international experience along the way.

Representing Fight Team MMA Brodnica, Karol brings into the cage a combination of fast pace, sharp striking, physical strength, and growing technical awareness. His confidence continues to rise with every fight, making him an increasingly dangerous challenge—even for seasoned veterans.

🔥 Why This Fight Is So Exciting

This matchup perfectly represents the essence of MMA:

• Mariusz Joniak brings years of experience, elite grappling, and composure under pressure.

• Karol Durszlewicz, our ambassador, represents the new generation—explosive, fearless, and determined to make a statement on the biggest stage.

With both fighters possessing finishing ability and contrasting styles, this bout has all the ingredients to deliver high-level action and possibly an early stoppage.

🗓️ XTB KSW 115 – February 21 in Lubin

The XTB KSW 115 event will take place on February 21, 2026, at the RCS Arena in Lubin. The gala will feature a stacked fight card and will be broadcast live, bringing top-tier MMA action to fans across Poland and beyond.

🥊 Summary

The fight between Mariusz Joniak and Karol Durszlewicz is a true clash of generations—experience versus momentum, patience versus explosiveness. Regardless of the outcome, fans can expect a thrilling contest that embodies the spirit of modern MMA.

February 21, 2026. Lubin. Stay ready with Środowisko Miejskie.
We’re always closer to the action. 🔥💪