National Bank Open: Marta Kostyuk vs Iga Swiatek

Platform comparison

Market context

Marta Kostyuk’s match with Iga Swiatek at the National Bank Open is priced with a modest upset chance, which fits the broader market split: the crowd-implied probability of 36% for Kostyuk is below several tennis previews and sportsbook-style lines that lean Swiatek. Tennis.com’s projected winner model gives Swiatek a 57% chance, while one betting preview lists Swiatek at about -142 and Kostyuk at +116, implying a favourite but not an overwhelming one.[2][14] That sits near the same range as other pre-match prediction pages, with most treating Swiatek as the likelier winner but not by a decisive margin.[12][15]

The historical frame is important because the head-to-head has been competitive enough to keep this from looking like a routine top-seed ticket. Published previews describe Swiatek leading the series 3-1, but Kostyuk won the most recent meeting at Roland-Garros in 2026, which is the sort of result that can keep prediction markets from drifting too far towards the favourite.[3][7][9] The context also matters: this is an outdoor hard-court match in Toronto, and both players were listed in the Round of 16 stage on the tournament schedule.[1][10]

Traders should watch the tournament’s own match updates and any schedule changes, because the contract only resolves to a split outcome if the match is cancelled, tied, or delayed beyond seven days without a winner.[1] The National Bank Open’s official results pages already show Swiatek and Kostyuk aligned for this round, while third-party live scoreboards have continued to publish the fixture as upcoming, which is useful for spotting any late withdrawal or postponement risk.[4][5][6] If the match is played, the main driver remains whether Swiatek’s baseline strength holds or whether Kostyuk can convert her recent head-to-head edge into another upset.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews National Bank Open: Marta Kostyuk vs Iga Swiatek across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to PolyGram, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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 PolyGram. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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 PolyGram trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.