San Marino: Vilius Gaubas vs Thiago Monteiro

Platform comparison

Market context

Vilius Gaubas and Thiago Monteiro meet in the San Marino quarter-final, and the contract is already pricing a complete Gaubas advance at **100% YES**. That is far more bullish than the broader tennis data would suggest: Monteiro has won the only two head-to-head meetings listed in the available match databases, both on clay, including a straight-sets win in Bad Waltersdorf in 2024 and a three-set win in Bastad in 2025.[7][8][5] By contrast, some prediction sites still lean towards Gaubas, with one model giving him about **58%** to win, which highlights a clear gap between market pricing and analyst-style priors.[17]

The historical frame for this contract is that head-to-head edge and clay-court profile matter, but they do not always map neatly onto an individual match market when the event is live and settlement rules are strict. Monteiro’s perfect record in the matchup and stronger clay results are the main reasons a full 100% price looks aggressive relative to model estimates and tennis-stat consensus.[7][2][16] In prediction markets, a quote at the ceiling often reflects either a late-stage result already being partially priced in or thin liquidity rather than a balanced assessment of true win probability.

For traders, the key catalysts are whether the match is officially completed, whether a retirement occurs, and whether the ATP/San Marino schedule changes affect settlement timing. The listed quarter-final pairing appears on tournament and score-tracking pages, which supports the event being on the card, but the contract’s fallback to 50-50 if the match is not played or is delayed beyond seven days means any interruption before a winner is recorded matters more than normal pre-match form.[12][1] The live score and official tournament pages are the main items to watch for a confirmed result path.[1][12]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

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.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

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.