Win probability

Wednesday, 26 August 2026

20 matches selected · 2 tournaments · model last ran 01:50 UTC

Umpiry rates 20 matches on Wednesday, 26 August 2026. The closest is Katie Swan 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
23:00US Open
WTA · hard
Q64Swan K.Stoiana M.50 %50 %Toss-up0–1
19:30US Open
WTA · hard
Q64Jorge F.Ristic M.50 %50 %Toss-up0–1
01:15US Open
ATP · hard
Q256Echargui M.Dellien H.51 %49 %Toss-up0–1
01:40US Open
WTA · hard
Q64Costoulas S.Kalieva E.52 %48 %Toss-up1–2
19:30US Open
WTA · hard
Q64Papamichail D.Gorgodze E.53 %47 %Toss-up0–4
19:30US Open
ATP · hard
Q64Wendelken H.Bertola R.53 %47 %Toss-up1–2
22:00US Open
WTA · hard
Q64Havlickova L.Uchijima M.53 %47 %Toss-up1–0
00:11US Open
ATP · hard
Q64Gojo B.Yunchaokete B.54 %46 %Toss-up0–3
22:30US Open
WTA · hard
Q64Maristany Zuleta De Reales G.Zidansek T.55 %45 %Toss-up0–3
18:00US Open
WTA · hard
Q64Montgomery R.Vandromme J.55 %45 %Toss-up1–0
22:20US Open
ATP · hard
Q256Glinka D.Martinez P.55 %45 %Toss-up1–1
21:30US Open
WTA · hard
Q64Andreescu B.Podrez V.57 %43 %Toss-up1–0
19:30US Open
WTA · hard
Q64Pareja J.Shymanovich I.57 %43 %Toss-up1–0
18:00US Open
ATP · hard
Q64Guerrieri A.Schwaerzler J.57 %43 %Toss-up1–1
18:00US Open
WTA · hard
Q64Hontama M.Lazaro Garcia A.60 %40 %Slight edge0–1
21:30US Open
ATP · hard
Q64Passaro F.Gentzsch T.62 %38 %Slight edge1–0
19:30US Open
ATP · hard
Q64Ymer E.Garin C.62 %38 %Slight edge0–3
01:50US Open
WTA · hard
Q64Valdmannova V.Sasnovich A.62 %38 %Slight edge1–0
00:20US Open
ATP · hard
Q256Smith C.Pellegrino A.63 %37 %Slight edge1–0
02:02US Open
WTA · hard
Q64Shubladze A.Semenistaja D.65 %35 %Slight edge0–1

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

Tuesday, 25 August 2026 · 20 matches

Favourites won

7 / 20

Model expected

11.0

The model expected 11.0 favourites to win; 7 did. See yesterday’s page.

Biggest shock, last 7 days

25 Aug
M25 Oviedo
ITF · clay
R32

Surprise score

81

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.