Pronóstico: National Bank Open: Marta Kostyuk vs Madison Keys

Platform comparison

Market context

Polymarket is pricing the Marta Kostyuk side at **98% YES** on a contract settled in **USDC** on Polygon, which means the market is treating Kostyuk as an overwhelming favourite to advance in this National Bank Open match. For a user holding conditional tokens, that price implies only a small residual chance that Madison Keys progresses, or that an outcome-triggering disruption changes settlement terms.

The current screen is not fully aligned with comparable tennis probabilities elsewhere: Tennis.com’s match page shows Kostyuk as the projected winner at 57%, while other preview and prediction pages have Keys drawing support because of the head-to-head. Sportschau lists Keys leading the rivalry 2-0, with four sets won to none, which is the clearest historical counterweight to a near-certain Polymarket price.[1][6][14] In other words, the contract is trading far more decisively than the broader tennis commentary, so the market is heavily discounting upset risk rather than reflecting a balanced contest.

For traders, the main catalysts are straightforward: the official match status, any delayed start or rescheduling on the National Bank Open schedule, and whether the contest is completed under normal tournament conditions. The tournament’s own results page and live match listings show Kostyuk v Keys set for the Grandstand, while live score services track the match in real time, which matters because a match that is not played, or is delayed beyond seven days without a winner, resolves to 50-50 under the market rules.[7][10][5] If the match begins but cannot be finished, the eventual advancement decision is still decisive for settlement, so any retirement or walkover update from the event feed is the key thing to watch.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Pronóstico: National Bank Open: Marta Kostyuk vs Madison Keys across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Polymarket Qué Es. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Polymarket Qué Es trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.