Win probability

Tuesday, 25 August 2026

20 matches selected · 3 tournaments · model last ran 22:50 UTC

Umpiry rates 20 matches on Tuesday, 25 August 2026. The closest is Harmony Tan v Mary Stoiana at 50 % — the model’s most uncertain call of the day. Probabilities come from a per-tour model trained on Elo, surface Elo, recent serve and return form and layoff.

Rated matches · ordered closest first
TimeTournamentRoundMatchProbabilityVerdictH2H
00:25US Open
WTA · hard
Q128Tan H.Stoiana M.50 %50 %Toss-up0–1
02:20US Open
ATP · hard
Q256Svajda T.Pinnington Jones J.50 %50 %Toss-up1–2
22:20US Open
WTA · hard
Q128Astakhova D.Bassols Ribera M.50 %50 %Toss-up0–1
19:30US Open
ATP · hard
Q256Mmoh M.Rocha H.51 %49 %Toss-up0–1
22:26US Open
WTA · hard
Q128Garland J.Romero Gormaz L.51 %49 %Toss-up1–0
22:05US Open
WTA · hard
Q128Prozorova T.Liutova K.51 %49 %Toss-up0–1
23:00US Open
ATP · hard
Q128Neumayer L.Crawford O.52 %48 %Toss-up1–1
22:30US Open
WTA · hard
Q128Osuigwe W.Barthel M.52 %48 %Toss-up0–1
18:02US Open
ATP · hard
Q256Skatov T.Arnaud Bailly G.53 %47 %Toss-up1–0
19:55US Open
ATP · hard
Q256Sanchez Izquierdo N.Mikrut L.53 %47 %Toss-up0–1
00:10US Open
WTA · hard
Q128Sebov K.Avdeeva J.55 %45 %Toss-up0–1
06:00Monterrey
WTA · hard
R32Vekic D.Parry D.55 %45 %Toss-up1–2
22:35US Open
ATP · hard
Q256Sakellaridis S.O'Connell C.56 %44 %Toss-up0–1
01:40US Open
ATP · hard
Q256Djere L.Muller A.56 %44 %Toss-up1–1
00:35US Open
WTA · hard
Q128Inglis M.Hunter S.56 %44 %Toss-up2–3
19:30US Open
WTA · hard
Q128Bandecchi S.Charaeva A.57 %43 %Toss-up3–2
01:50US Open
WTA · hard
Q128Andrea Knutson G.Lepchenko V.57 %43 %Toss-up1–0
18:00US Open
ATP · hard
Q256Nishikori K.Ofner S.63 %37 %Slight edge1–1
18:00US Open
ATP · hard
Q256Squire H.Jorda Sanchis D.65 %35 %Slight edge0–1
00:15US Open
ATP · hard
Q128Sakamoto R.Zhang Z.69 %31 %Clear favourite0–1

How to read this

Each row gives the model’s probability that the favourite wins, and the verdict says the same thing in words. Rows are ordered by how close the model thinks the match is, so the top of the table is where it is least sure. A 70 % favourite losing is not a broken model — it is the 30 %. Probabilities are not odds and take no account of any market.

How often the model has been right

Umpiry win-probability model accuracy by tour family, measured on the predictions the model made
TourCorrect
ATP / WTA66 %
Challenger (men)64 %
Challenger (women)68 %
ITF (men)66 %
ITF (women)64 %

Measured on the predictions the model actually made, not on a backtest — see Methodology.

Yesterday

Monday, 24 August 2026 · 20 matches

Favourites won

13 / 20

Model expected

11.2

The model expected 11.2 favourites to win; 13 did. See yesterday’s page.

Biggest shock, last 7 days

24 Aug
Philly Open - Philadelphia
CHALLENGER · hard
R32

Surprise score

89

Questions

How is the probability calculated?
A separate model for each tour, trained on Elo, surface-specific Elo, recent serve and return form and time since the player’s last match. It runs several times a day; the time of the last run is at the top of this page.
How often is the model right?
We publish it. The table above gives the hit rate for each tour family, measured on the predictions the model actually made — see Methodology for how it is computed.
Why are the closest matches at the top?
Rows are ordered by distance from 50 %, so the table opens where the model is least sure. “Most one-sided” reverses the order and groups the rows by tournament.
Is this a betting tip?
No. The page shows a model’s probability and how often that model has been right. There are no odds, no comparison with a market and no suggested stake.