Win probability

Friday, 4 September 2026

20 matches selected · 4 tournaments · model last ran 21:50 UTC

Umpiry rates 20 matches on Friday, 4 September 2026. The closest is Fajing Sun v Chun Hsin Tseng at 52 % — the model’s most uncertain call of the day. The most one-sided is Aryna Sabalenka v Kamilla Rakhimova at 95 %. 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
07:30Zhangjiagang
CHALLENGER · hard
QFSun F.Hsin Tseng C.52 %48 %Toss-up0–1
12:00Plovdiv 3
CHALLENGER · clay
QFOvcharenko O.Kravchenko G.53 %47 %Toss-up0–2
18:00US Open
WTA · hard
R32Cirstea S.Paolini J.60 %40 %Slight edge1–3
19:30US Open
WTA · hard
R32Shnaider D.Townsend T.61 %39 %Slight edge0–1
23:55US Open
ATP · hard
R32Etcheverry T.Navone M.64 %36 %Slight edge3–0
19:30US Open
ATP · hard
R32Paul T.Bublik A.64 %36 %Slight edge6–2
01:17US Open
ATP · hard
R64Bergs Z.De Jong J.64 %36 %Slight edge2–0
00:25US Open
ATP · hard
R32Michelsen A.Merida Aguilar D.68 %32 %Clear favourite2–1
21:45US Open
WTA · hard
R32Muchova K.Navarro E.72 %28 %Clear favourite0–1
19:30US Open
ATP · hard
R32Medvedev D.Rinderknech A.75 %25 %Clear favourite2–1
23:30US Open
ATP · hard
R64De Minaur A.Van De Zandschulp B.75 %25 %Clear favourite4–1
02:00US Open
ATP · hard
R64Tien L.Monfils G.79 %21 %Clear favourite2–0
21:15US Open
WTA · hard
R32Noskova L.Li A.80 %20 %Clear favourite2–0
18:30US Open
WTA · hard
R32Pegula J.Fernandez L.83 %17 %Strong favourite4–1
02:00US Open
WTA · hard
R64Gauff C.Badosa P.84 %16 %Strong favourite4–5
18:00US Open
WTA · hard
R32Kostyuk M.Alexandrova E.85 %15 %Strong favourite1–2
04:00US Open
WTA · hard
R64Rybakina E.Bouzas Maneiro J.92 %8 %Strong favourite2–0
03:45US Open
ATP · hard
R64Zverev A.Halys Q.92 %8 %Strong favourite3–0
21:00US Open
ATP · hard
R32Alcaraz C.Wu Y.94 %6 %Strong favourite2–0
18:00US Open
WTA · hard
R32Sabalenka A.Rakhimova K.95 %5 %Strong favourite4–0

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, 3 September 2026 · 20 matches

Favourites won

17 / 20

Model expected

14.7

The model expected 14.7 favourites to win; 17 did. See yesterday’s page.

Biggest shock, last 7 days

3 Sept
W15 Brasov
ITF · clay
R16

Surprise score

92

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.