Resolution criteria on PolyGram: This market refers to the tennis match between Jan Jermar and Garrett Johns in the Ostrava, originally scheduled for April 28, 2026 at 4:00AM ET. This market will resolve to 'Jan Jermar' if Jan Jermar advances against Garrett Johns. This market will resolve to 'Garrett Johns' if Garrett Johns advances against Jan Jermar. If the match is canceled (not played at all), ends in a tie, or is delayed beyond 7 days from the scheduled date without a winner determined, this market will resolve to 50-50. If the match begins but is not completed, and one player advances due to the opponent's retirement, default, or disqualification, this market will resolve to the player who advances.
PolyGram is an on-chain prediction market where you trade YES or NO outcome shares with real USDC on Polygon. For this market, buy YES if you believe the event will happen, or NO if you think it won't. Your maximum loss is your stake — winning shares pay $1.00 each at resolution. Unlike sportsbooks, there is no house edge: prices are set by supply and demand from other traders and reflect the crowd's real-time probability.
Market outcomes
| Ostrava: Jan Jermar vs Garrett Johns | 0% YES | 100% NO |
| Ostrava: Jan Jermar vs Garrett Johns Set 1 O/U 8.5 | 0% YES | 100% NO |
| Ostrava: Jan Jermar vs Garrett Johns Set 1 Winner | 0% YES | 100% NO |
| Ostrava: Jan Jermar vs Garrett Johns Match O/U 21.5 | 0% YES | 100% NO |
| Ostrava: Jan Jermar vs Garrett Johns Set 1 O/U 9.5 | 0% YES | 100% NO |
| Ostrava: Jan Jermar vs Garrett Johns Match O/U 22.5 | 0% YES | 100% NO |
| Ostrava: Jan Jermar vs Garrett Johns Total Sets: O/U 2.5 | 0% YES | 100% NO |
| Ostrava: Jan Jermar vs Garrett Johns Set 1 O/U 10.5 | 0% YES | 100% NO |
Jan Jermar and Garrett Johns are scheduled to compete in a tennis match at the Ostrava tournament on 28 April 2026, with the market settlement window closing on 5 May. The 0% implied probability on the order book reflects either minimal trading activity or a strong consensus that one player is heavily favoured, though the sparse liquidity typical of niche tennis matchups means the current price may not represent deep conviction. Polymarket's order book shows no meaningful YES position accumulation, suggesting traders are either avoiding the market entirely or positioning exclusively on the alternative outcome.
Jermar, a Czech player competing in his home region, typically benefits from crowd support and familiarity with local conditions at Ostrava events. Johns, an American competitor, faces the standard disadvantages of travel and unfamiliar surfaces. Historical ATP Challenger and lower-tier tour data indicates home-nation players in Eastern European clay tournaments win approximately 58–62% of matches against overseas opponents of comparable ranking, though individual matchup dynamics vary significantly based on recent form and head-to-head records.
Traders should monitor both players' performance in the weeks preceding the tournament, particularly results from late April warm-up events that would signal current fitness and confidence levels. Injury announcements or withdrawal declarations would trigger resolution mechanics outlined in the market terms. The tight settlement window—only seven days after the scheduled date—means any significant delay or postponement could activate the 50-50 tie resolution clause, a material risk factor for positions held through early May.
This market settles from the official outcome published at https://www.atptour.com/en/scores/current. A proposer submits the final result to the UMA optimistic oracle on Polygon; the two-hour dispute window closes and payouts clear in USDC.
The mechanics for trading "Ostrava: Jan Jermar vs Garrett Johns" are the same as any other PolyGram sporting event contract. Each YES share resolves to $1 if the event happens, or $0 if it doesn't. The current price between 0¢ and 100¢ is the market's probability estimate, set live by the order book.
$7K in lifetime turnover and $0 of resting liquidity puts this market in the below the median by volume for sports contracts on PolyGram. Order-book depth is thin — large orders may need to be split across the book or executed as limit orders.
The market has been open for under a month — fresh enough that information asymmetry remains a real factor.
Higher-volume markets tend to have tighter spreads and faster price discovery — meaning the displayed YES/NO percentages are more likely to reflect the true crowd-implied probability rather than a single trader's directional view.
Resolution is sourced from https://www.atptour.com/en/scores/current. Settlement is executed by the UMA optimistic oracle on Polygon, with a 2-hour dispute window before payouts clear.
This prediction market is scheduled to close on 5 May 2026. After the resolving event occurs, settlement typically clears within 24 hours once the UMA optimistic oracle confirms the outcome. All payouts are in USDC on the Polygon network.
To trade on this prediction market, create a free PolyGram account at polygram.ink, deposit USDC via Polygon, and place a YES or NO order on the outcome you believe in. You can learn more on our how-it-works page. Your maximum loss is limited to your stake — there is no leverage or margin.
When the outcome is determined, winning YES shares pay out $1.00 each in USDC, while losing shares pay $0. Settlement is handled by the UMA optimistic oracle on Polygon — a proposer submits the result, a two-hour dispute window opens, and if uncontested, payouts are distributed automatically. You can withdraw your winnings to any Polygon wallet.
Prediction-market positions can lose 100% of staked capital. Outcomes are uncertain by definition — historical accuracy of crowd-implied probabilities is high in aggregate but not for any single market. PolyGram does not provide investment advice. Trade only with capital you can afford to lose.
Regulatory status varies by jurisdiction. Germany, the United States, and most EU countries treat Polymarket-style event contracts under one of three frameworks: financial derivative, gambling product, or unregulated novel asset. Consult local counsel before trading.
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