National Bank Open: Maria Sakkari vs Coco Gauff

Platform comparison

Market context

Coco Gauff’s meeting with Maria Sakkari in Toronto has already been priced as a strong Gauff position on both traditional books and market platforms, which helps explain why a 0% YES reading on Polymarket looks like an outlier rather than a consensus view. Recent market references have had Gauff around 1.20–1.29 decimal odds, versus roughly 3.64–4.25 for Sakkari, which converts to a clear favourite but not a certainty; by contrast, Kalshi shows the same matchup in cents terms, with Gauff near 78–79¢ and Sakkari around 22¢, while Polymarket and similar event contracts typically display the probability directly.[3][8][14]

The historical frame also leans towards Gauff. In recent previews and model outputs, Gauff has been assessed in the mid-70s to low-80s percentage range, and a 2025 Toronto/Indian Wells comparison showed the market consistently favouring her by a wide margin even when Sakkari’s price was inflated by matchup volatility.[2][6][9][18] On Betfair or Smarkets, that kind of edge usually appears as back/lay prices with commission deducted from winnings, so the headline odds can look slightly shorter than the true break-even once fees are included; on Kalshi-style contracts, the fee impact is usually separate from the displayed contract price, which makes cross-platform comparisons less direct.

For traders, the main catalyst is whether the match is actually played and completed before the settlement window closes, because a cancellation, tie, or delay beyond seven days resolves to 50-50 under the market rules. The scheduled start was August 6 at 11:00 a.m. ET, so any late court assignment, withdrawal, walkover, or injury update matters more than normal pre-match noise, especially with Toronto draws often moving on condensed scheduling.[14][18] Reuters did not appear in the available results, so the most relevant live signals here are official order-of-play updates, tournament injury reports, and any platform-specific settlement notices, particularly on whether a retirement after the match starts counts as an advancing winner under the contract terms.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares National Bank Open: Maria Sakkari vs Coco Gauff specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. The live probability is the Polymarket mid; the comparison columns summarise each venue's fee structure, KYC, settlement currency and payment rails. Every CTA routes to Robinhood Prediction Markets, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

What does Polymarket cost vs Kalshi?

Polymarket: 0% fees, only Polygon network costs (~$0.01/trade). Kalshi: up to 7% per trade plus spread. For high-frequency traders, Polymarket is dramatically cheaper.

Which platform has the deepest liquidity?

Polymarket — by a wide margin. Top markets reach $50-500M volume, Kalshi ~$200M cumulative, Betfair similar. Deeper liquidity means your trade moves the quote less.

Is Betfair a Polymarket alternative?

Only partially. Betfair Exchange is UK-focused with a sports-betting emphasis; they have politics markets but with thinner liquidity than Polymarket. Settlement in GBP/EUR, 2-5% commission on winnings.

Which platform is accessible globally?

Polymarket is geo-blocked in the US/UK/EU. Kalshi is US-only. Betfair and Smarkets are UK-restricted. Robinhood Prediction Markets has a different geo footprint and routes to Polymarket's order book at 0% fees.

Are all these platforms regulated?

No. Kalshi is CFTC-regulated (US). Betfair and Smarkets are UK Gambling Commission licensed. Polymarket operates without explicit regulation — a different risk profile than a regulated sportsbook.