Stoiana vs Siniakova: Osaka model and market split
Siniakova's ranking supports favoritism in Osaka, but Stoiana's recent form and return record make the case for a tighter contest.
52% is Court Shark's model probability for Katerina Siniakova in the Osaka quarterfinal, a narrow edge rather than a strong favorite's position. Her ranking supports favoritism, but Mary Stoiana's recent results and hard-court return record support a closer match.
The disagreement is about the size of Siniakova's edge
The market consensus gives Katerina Siniakova a 69% chance, leaving a 17 percentage point gap against Court Shark's estimate. Both favor her. The disagreement concerns how much separation there is between her and Mary Stoiana, rather than which player should start as the favorite. That distinction matters for a match with evidence pointing in both directions.
The price moved 2 points toward Siniakova from the opening consensus. That establishes the direction of market expectations, but it cannot explain the reason for the move or identify which part of her game prompted it. The movement strengthened an existing preference rather than reversing the order of the players.
Siniakova is ranked No. 86, while Stoiana is No. 114. That offers a straightforward basis for putting Siniakova ahead, although the ranking order alone does not establish how wide the difference should be on this surface. My reading is that her stronger standing supports the favorite's label. Stoiana's results provide the clearest argument against making that label too strong.
Model and market on Mary Stoiana
Article snapshot, Oct 22, 2026 · Not live
Mary Stoiana's chance as the market consensus priced it from the opening line, next to the Court Shark model.
| Reading | Mary Stoiana | Katerina Siniakova |
|---|---|---|
| Opening consensus | 33% | 67% |
| Latest consensus | 31% | 69% |
| Court Shark model | 48% | 52% |
Stoiana brings the stronger recent record
Stoiana has gone 7-3 over her latest matches, compared with Siniakova's 5-5. Their recent hard-court records follow the same pattern, making Stoiana's form relevant to the conditions in Osaka rather than an achievement confined to another surface. Form favors Stoiana here. Those records do not adjust for opponent strength, so they cannot by themselves establish that she has played the better tennis.
Her four-match winning run includes a deciding set victory over Moyuka Uchijima after straight-set wins in her earlier Osaka matches. That is useful evidence of progress through this event, with her latest match requiring recovery after losing the middle set. It also means her current run has survived a setback within a match, rather than consisting entirely of uninterrupted control.
For Siniakova, a two-match winning run includes her latest victory over Magda Linette in straight sets. Her preceding victory over Peyton Stearns ended in a retirement, which limits how much that result says about her ability to finish a full contest. The Linette win is a cleaner positive signal. It gives Siniakova a current result to set against Stoiana's longer run, without erasing the broader contrast in recent consistency.
Recent form
Article snapshot, Oct 22, 2026 · Not live
Each player's most recent completed matches, up to 10, oldest on the left.
| Player | Date | Result | Opponent | Score | Event |
|---|---|---|---|---|---|
| Mary Stoiana | Sep 2, 2026 | L | Alexandra Eala | 1-6 2-6 | US Open |
| Mary Stoiana | Sep 9, 2026 | W | Jazmin Ortenzi | 6-3 6-2 | Barranquilla 125 |
| Mary Stoiana | Sep 10, 2026 | L | Julia Riera | 6-4 6-7(7) 3-6 | Barranquilla 125 |
| Mary Stoiana | Sep 16, 2026 | W | Claire Liu | 6-3 7-5 | Sao Paulo |
| Mary Stoiana | Sep 17, 2026 | W | Dominika Salkova | 7-6(5) 6-1 | Sao Paulo |
| Mary Stoiana | Sep 18, 2026 | L | Paula Badosa | 4-6 2-6 | Sao Paulo |
| Mary Stoiana | Oct 17, 2026 | W | Rinko Matsuda | 6-3 7-6(1) | WTA Osaka |
| Mary Stoiana | Oct 18, 2026 | W | Sayaka Ishii | 6-4 7-5 | WTA Osaka |
| Mary Stoiana | Oct 20, 2026 | W | Oleksandra Oliynykova | 6-2 6-3 | WTA Osaka |
| Mary Stoiana | Oct 22, 2026 | W | Moyuka Uchijima | 6-2 2-6 6-3 | WTA Osaka |
| Katerina Siniakova | Aug 4, 2026 | L | Kamilla Rakhimova | 7-6(1) 0-6 2-5 RET | Toronto |
| Katerina Siniakova | Aug 16, 2026 | W | Jessica Bouzas Maneiro | 6-7(5) 6-1 6-1 | Cincinnati |
| Katerina Siniakova | Aug 18, 2026 | L | Madison Keys | 1-6 3-6 | Cincinnati |
| Katerina Siniakova | Aug 31, 2026 | W | Elisabetta Cocciaretto | 6-3 6-2 | US Open |
| Katerina Siniakova | Sep 3, 2026 | L | Naomi Osaka | 2-6 7-5 1-6 | US Open |
| Katerina Siniakova | Oct 1, 2026 | W | Magda Linette | 6-4 6-3 | Beijing |
| Katerina Siniakova | Oct 3, 2026 | L | Elina Svitolina | 6-1 4-6 2-6 | Beijing |
| Katerina Siniakova | Oct 13, 2026 | L | Liudmila Samsonova | 1-6 7-5 2-6 | Wuhan |
| Katerina Siniakova | Oct 20, 2026 | W | Peyton Stearns | 6-4 0-6 4-0 RET | WTA Osaka |
| Katerina Siniakova | Oct 22, 2026 | W | Magda Linette | 6-4 6-1 | WTA Osaka |
Watch whether Stoiana can pressure Siniakova's serve
On hard courts, Stoiana has broken serve in 41% of return games, against Siniakova's 37%. That supports a concrete route for the underdog: keeping Siniakova from building comfortable service holds and making her defend repeatedly. Return pressure matters here. These samples cover different opponents and are not a direct measurement of how either player will return against the other.
On serve, Siniakova has held 66% of games in the hard-court sample, compared with Stoiana's 64%. I read that as a modest serving advantage rather than a decisive separation, especially alongside Stoiana's stronger return figure. Early service games should help test that reading. Comfortable holds for Siniakova would weaken the case that Stoiana can turn her return record into sustained pressure.
There is no previous meeting to establish a matchup pattern, so neither player has a direct record of solving the other's game. Watch whether Stoiana can protect serve while creating chances on return, rather than judging her prospects only by occasional breaks. If Siniakova repeatedly holds without pressure and attacks Stoiana's service games, the case for a close contest would become less persuasive.
Explore this matchup
Compare both players side by side: recent results, surfaces, serve and return.
Player comparison
Article snapshot, Oct 22, 2026 · Not live
Each measure on the same scale: recent wins, wins on this surface, head-to-head wins and the model's chance.
| Measure | Mary Stoiana | Katerina Siniakova |
|---|---|---|
| Wins, last 10 matches | 70% (7-3) | 50% (5-5) |
| Wins, last 10 on hard | 70% (7-3) | 50% (5-5) |
| Model win probability | 48% | 52% |
Win rate by surface
Article snapshot, Oct 22, 2026 · Not live
Share of matches won on each surface across each player's last 50 matches with full statistics.
| Surface | Mary Stoiana | Katerina Siniakova |
|---|---|---|
| Hard | 60% (15-10) | 54% (20-17) |
| Clay | 67% (10-5) | 50% (3-3) |
| Grass | 70% (7-3) | 57% (4-3) |
Serve and return on hard courts
Article snapshot, Oct 22, 2026 · Not live
How often each player held serve and broke serve on hard over their last 50 matches with full statistics, against the tour's all-years average on the surface.
| Measure | Mary Stoiana | Katerina Siniakova | Tour average, all years |
|---|---|---|---|
| Service games held | 64% | 66% | 63% |
| Return games broken | 41% | 37% | 37% |
| Matches in sample | 25 | 37 |
Model win probability
Article snapshot, Oct 22, 2026 · Not live
The Court Shark model's chance for each player to win this match.
| Player | Win probability | Recent form (last 10) |
|---|---|---|
| Mary Stoiana | 48% | 7-3 |
| Katerina Siniakova | 52% | 5-5 |
Ways to win
Article snapshot, Oct 22, 2026 · Not live
Every way the match can finish. The likeliest single result is Katerina Siniakova in straight sets (34%).
| Result | Chance |
|---|---|
| Mary Stoiana wins 2-0 | 30% |
| Mary Stoiana wins 2-1 | 18% |
| Katerina Siniakova wins 2-1 | 18% |
| Katerina Siniakova wins 2-0 | 34% |
How long it could go
Article snapshot, Oct 22, 2026 · Not live
A 60% chance the match lasts 17 to 27 games; 21 is the middle of the range.
| Total games | Chance |
|---|---|
| 12 | 0.3% |
| 13 | 1.2% |
| 14 | 2.8% |
| 15 | 5.0% |
| 16 | 7.4% |
| 17 | 8.7% |
| 18 | 8.6% |
| 19 | 7.9% |
| 20 | 6.8% |
| 21 | 5.1% |
| 22 | 5.8% |
| 23 | 3.7% |
| 24 | 2.3% |
| 25 | 3.8% |
| 26 | 3.9% |
| 27 | 3.8% |
| 28 | 4.0% |
| 29 | 4.1% |
| 30 | 3.8% |
| 31 | 3.3% |
| 32 | 2.8% |
| 33 | 1.8% |
| 34 | 1.3% |
| 35 | 1.1% |
| 36 | 0.5% |
Service games held: where they stand
Article snapshot, Oct 22, 2026 · Not live
Each dot is one of the WTA top 100 with enough matches in the last 52 weeks. Mary Stoiana ranks ahead of 1 of 64; Katerina Siniakova ranks ahead of 20 of 64.
| Player | Service games held | Place |
|---|---|---|
| Mary Stoiana | 54.3% | Ahead of 1 of 64 |
| Katerina Siniakova | 66.4% | Ahead of 20 of 64 |
| Field median | 69.5% | |
| Field best (Elena Rybakina) | 83.0% | 1st |
Two years of form
Article snapshot, Oct 22, 2026 · Not live
Each player's pre-match Elo rating since Jan 4, 2025. Latest: Katerina Siniakova 1745 (Oct 20, 2026), Mary Stoiana 1708 (Oct 20, 2026).
| Player | Start of window | Two-year peak | Latest |
|---|---|---|---|
| Mary Stoiana | 1500 (Jan 8, 2025) | 1708 (Oct 20, 2026) | 1708 (Oct 20, 2026) |
| Katerina Siniakova | 1675 (Jan 4, 2025) | 1787 (Oct 10, 2025) | 1745 (Oct 20, 2026) |
Court Shark win probabilities are statistical estimates, not advice. No outcome is guaranteed.
Methodology and sources
How we build model estimates and where our information comes from.
Model estimates and observed results
The win probabilities come from the Court Shark match model, trained on completed ATP and WTA matches. A probability says how often a player in this position wins, not that one result will happen. The model's number for a match is recorded before play and never changed afterwards, so it can be checked against the result.
Sources and citations
Results, scores, rankings and serve statistics come from the Court Shark match database. The market consensus is the pre-match price for each player converted to a probability. Figures in this article are a snapshot taken when it was written.
Limitations
Serve and return rates count only matches with full serve statistics, which are sparser for Challenger and lower-level events, and the tour average they are compared with covers every year on record. Head-to-head records count every meeting with a recorded winner, walkovers and retirements included. Charts and tables are a snapshot and do not update after publication.
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