Win probability

Friday, 28 August 2026

20 matches selected · 3 tournaments · model last ran 16:50 UTC

Umpiry rates 20 matches on Friday, 28 August 2026. The closest is C. O'Connell v Zsombor Piros at 50 % — the model’s most uncertain call of the day. The most one-sided is Bianca Andreescu v Tamara Zidansek at 71 %. 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
18:00US Open
ATP · hard
Q32O'Connell C.Piros Z.50 %50 %Toss-up0–2
18:00US Open
ATP · hard
Q32Gaubas V.Wendelken H.51 %49 %Toss-up0–1
19:15US Open
ATP · hard
Q32Schoolkate T.Draxl L.51 %49 %Toss-up1–0
18:00US Open
ATP · hard
Q32Mochizuki S.Passaro F.52 %48 %Toss-up0–2
19:30US Open
WTA · hard
Q64Yuan Y.Stoiana M.53 %47 %Toss-up0–1
18:05US Open
WTA · hard
Q64Hunter S.Semenistaja D.54 %46 %Toss-up1–2
18:00US Open
ATP · hard
Q32Svrcina D.Mcdonald M.55 %45 %Toss-up1–0
18:05US Open
ATP · hard
Q32Basavareddy N.Gea A.55 %45 %Toss-up1–0
19:00US Open
ATP · hard
Q32Nishikori K.Sakamoto R.56 %44 %Toss-up0–1
19:10US Open
ATP · hard
Q32Yunchaokete B.Cina F.56 %44 %Toss-up1–1
18:05US Open
WTA · hard
Q64Kubka M.Liutova K.56 %44 %Toss-up0–1
18:00US Open
WTA · hard
Q64Koevermans A.Bolkvadze M.57 %43 %Toss-up1–0
19:00US Open
WTA · hard
Q64Sakatsume H.Ristic M.57 %43 %Toss-up1–0
19:30US Open
WTA · hard
Q64Jones F.Garland J.57 %43 %Toss-up1–0
21:30US Open
WTA · hard
Q64Havlickova L.Hibino N.58 %42 %Toss-up1–1
19:30US Open
ATP · hard
Q32Gaston H.Smith C.60 %40 %Slight edge1–0
04:30Monterrey
WTA · hard
QFTauson C.Parry D.61 %39 %Slight edge0–3
18:00US Open
ATP · hard
Q32Harris L.Llamas Ruiz P.61 %39 %Slight edge3–0
19:35US Open
WTA · hard
Q64Valdmannova V.Kalieva E.61 %39 %Slight edge0–1
21:45US Open
WTA · hard
Q64Andreescu B.Zidansek T.71 %29 %Clear favourite0–2

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

Thursday, 27 August 2026 · 20 matches

Favourites won

15 / 20

Model expected

12.3

The model expected 12.3 favourites to win; 15 did. See yesterday’s page.

Biggest shock, last 7 days

27 Aug
M15 Pecs
ITF · clay
R16

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.