What is the Siniakova vs. Keys 21.5 games prediction market?

It is a tennis totals market on whether the match between Katerina Siniakova and Madison Keys will reach at least 22 completed games across all sets.

What does Over 21.5 mean in this tennis market?

Over wins if the total number of completed games is 22 or more. A total of 21 games or fewer results in Under.

How are tiebreaks counted?

Each tiebreak, including a Champions or Super tiebreak, counts as one game toward the match total.

When does the Siniakova vs. Keys market resolve?

The match is scheduled for August 18, 2026, and the market has a listed resolution date of August 25, 2026. If the match starts but is not completed, it resolves 50-50 under the market rules.

Is there smart money activity on this Polymarket tennis market?

PolySpotter records $1,388 in tracked smart money and one signal, with an experienced bettor buying the Over in the thinly traded market.

Part of: Cincinnati Open: Katerina Siniakova vs Madison Keys

Siniakova vs. Keys: Match O/U 21.5

This Cincinnati Open prediction market covers the total games in Katerina Siniakova vs. Madison Keys. The market resolves to Over if the match has at least 22 completed games, or Under if it has 21 or fewer; tiebreaks count as one game. The match is scheduled for August 18, 2026, and the provided data does not include current live odds.

1 smart money signal detected, totaling $1,388.

Categories: Tennis, Sports, Games

Notable Trades

Experienced bettor buys Over in thin market

A highly experienced, profitable serial trader placed a large Over bet in a very thin tennis market, creating a meaningful conviction signal despite only modest historical edge over entry prices.

This bettor has 92,986 resolved trades, a 70% win rate, and over $540,000 in reported profit.
The $1,388 Over bet was nearly 20 times the detected 24-hour volume, signaling notable conviction in a thin market.
The Over was bought at 49¢, implying the trader sees better than even odds while the market currently prices it at 47%.

$1,388 on Over | Wallet win rate: 70%

Top Holders

0x5b63...11a4 — Outcome 82736159, $4,298 (70% win rate)
0x91c8...a6bb — Outcome 82736159, $120
0xc4fe...601f — Outcome 82736159, $10
0x0309...d35e — Outcome 82736159, $5
0x1a31...0a68 — Outcome 82736159, $2

Related Theses

Türkiye avoids defeat

Covers 3 related markets

Brazil-Japan match will happen

Covers 3 related markets

Türkiye-US match gets played

Covers 3 related markets

Japan-Sweden match will happen

Covers 3 related markets

Several favorites could win the World Cup

Covers 7 related markets

Argentina will not win

Covers 3 related markets

Fed will cut rates in September

Covers 2 related markets

No deal by May

Covers 2 related markets

MicroStrategy sells Bitcoin in June

Covers 2 related markets

Iran avoids defeat vs New Zealand

Covers 3 related markets

Siniakova vs. Keys: Match O/U 21.5

ResolvedCincinnati Open: Katerina Siniakova vs Madison Keys$1,388 tracked1 signalTennisSportsGames

This market refers to the tennis match between Katerina Siniakova and Madison Keys in the Cincinnati Open, originally scheduled for August 18, 2026 at 10:00AM ET. This market will resolve to "Over" if the total number of games completed across all sets equals or exceeds 22. Otherwise, it will resolve to "Under." All tiebreaks—including any Champions/Super tiebreak—count as one (1) game toward the total. If the match begins but is not completed, this market will resolve 50-50. If the match is canceled before play begins or delayed beyond 7 days from the scheduled date without a result, this market will also resolve 50-50. Resolution will be based on official WTA statistics.

Price History — “Under”

87¢

70¢

52¢

Alert entriesHigh-conviction

Notable Trades