Sergiusz Zajac vs Mariusz Książkiewicz — ChatGPT betting tip 20 September 2025.

The market has drawn a firm line here: Sergiusz Zajac is the chalk at 1.41, while Mariusz Książkiewicz sits as the underdog at 2.70. Translating those numbers, Zajac’s price implies roughly a 70.9% break-even probability, and Książkiewicz about 37.0%. For a $1 stake, the favorite yields about $0.41 profit, the dog $1.70 profit. The question isn’t who is “better” in abstract terms—it’s whether the true win probability differs meaningfully from those thresholds. In MMA, where small gloves and short fights amplify variance, you often get paid to side with the right kind of underdog.

What makes this an actionable value approach is the combination of volatility and how favorites are frequently taxed in regional/main-card spots. Styles make fights: an underdog with solid fundamentals—responsible defense, a working jab and calf kicks, willingness to clinch, and competent takedown defense—can reliably steal minutes and swing close rounds. Add in opportunistic counters or a top-control sequence and the win condition materializes without needing a spectacular finish. If Książkiewicz can keep the exchanges honest, deny prolonged bad positions, and make Zajac work at his pace, he only needs to turn the judges in two rounds to cash the number.

By contrast, a price like 1.41 on the favorite assumes sustained dominance—clean entry to preferred positions, minimal defensive lapses, and pace-control from horn to horn. That’s not impossible, but it’s a high bar in a sport where one knockdown, a momentum-shifting scramble, or a late takedown can flip a scorecard. Unless Zajac brings a clear, repeatable edge—elite wrestling top time or a massive striking gap—the tax on the favorite looks rich.

From a betting perspective, the math lines up. At a conservative 42% true win chance for Książkiewicz, the expected value on 2.70 is positive: 0.42 × 1.70 − 0.58 × 1 ≈ +0.13 per $1 stake. Even if you shade him a touch lower, the combination of fight variance and the underdog’s multiple paths (minutes via clinch/control and moments via counters or level changes) makes this a preferable risk-reward to laying a steep price on a favorite who has to be near flawless.

One practical note: early read matters. If Książkiewicz shows composure—defending initial bursts, winning hand-fighting at range, and hand-fighting under hooks in the clinch—live markets often compress quickly. But pre-fight, for a single $1 wager, the value is on the plus money side. I’m taking the dog and letting the inherent volatility in MMA work for me rather than against me.

The pick: wager $1 on Mariusz Książkiewicz moneyline at 2.70. It’s the side that best balances realistic paths to victory with a price that doesn’t require perfection.