JapanWTA OsakaFinishedFeatured

Predictions graded

Katie Boulter #58United Kingdom0Katerina Siniakova #86Czechia2

Sets 1-6 · 4-6Sat 24 Oct 2026, 07:50 Predictions gradedSemi-FinalHard

Predictions7–370%

Edges5–271%

Player Profiles

Ranking advantageKatie Boulter · 28 places

Katie Boulter

United Kingdom

Boulter, 30, is the right-hander in this matchup. She reached a career-high No. 23 on November 4, 2024; her WTA profile lists Michael Joyce as coach.

Current ranking: #58
Peak ranking: #23 · 2024
Current age: 30
Preferred surface: Carpet
Hand: Right handed
Height: 182 cm

Katerina Siniakova

Czechia

Reached a career-high singles ranking of No. 27 in June 2024. Current context is dominated by the knee-related break reported on July 27, 2026.

Current ranking: #86
Peak ranking: #27 · 2024
Current age: 30
Preferred surface: Carpet
Hand: Right handed
Height: 174 cm

Quick Take

Pre-match view

Context last updated 23 Oct 2026, 21:51 · Europe/Bucharest

Osaka's semifinal pits Boulter's three-win week and a 4-6 6-2 6-1 win in the pair's only meeting against Siniakova's grip on second sets, seven of nine on hard since mid-August.

Siniakova is the narrow favourite to reach the final, though Boulter's 2.5-game start holds up better than the 1.6 on Siniakova. Three prices offer something: Boulter +2.5 games at 1.85, under 20.5 games at 2.2 and Boulter to win at 2.3.

Context

One of Siniakova’s three Osaka matches ended before completion, while Boulter needed three sets in her quarterfinal. That creates an asymmetric workload detail immediately before this semifinal. The retirement establishes a shortened match, but it does not provide exact court time or a player availability concern for Siniakova.
- Siniakova reached the semifinal with two straight-set victories and a retirement win over Stearns.
ReportedSources checked 23 Oct 2026, 21:49 · Europe/BucharestTennis Temple match pageen.tennistemple.com · 23 Oct 2026
The pair have met once, in April 2025, and Boulter lost the first set before taking the next two 6-2 and 6-1. One match more than a year old is thin evidence, but it is the only direct form guide here and it favours Boulter's ability to solve problems inside a match. Siniakova's week in Osaka has been the cleaner of the two.
- Boulter beat Siniakova 4-6 6-2 6-1 on 22 April 2025 in their only listed meeting.
Siniakova's first sets in this window have stayed close, but she has pulled away after the changeover. That makes the second set the clearest separation between the two players, given Boulter's four wins and nine losses in hard-court second sets over 13 matches. Nine completed matches is a short run, and two retirements were removed from the sample.
- Siniakova has won 7 of 9 second sets across nine completed hard-court matches between 16 August and 23 October 2026, averaging 5.7 games won to 3.4 lost.
- In the same nine matches her first sets are 5-4, at 4.4 games won to 4.2 lost.
- Two retirements were excluded from the nine-match sample.
Boulter's first serve earns 63.5% of points, but the second serve drops to 41% and 6.9 double faults a match give opponents regular entry into her service games. Siniakova's second-set strength is the part of her game best placed to use that. Fourteen charted matches is a reasonable sample, though several of them were heavy defeats to top-15 opposition.
- Boulter won 41.0% of second-serve points (167 of 407) across 14 matches with charted data among her last 15.
- She averaged 6.9 double faults per match (97 in 14 matches) and won 63.5% of first-serve points (364 of 573).

BetBugs edges

Compare BetBugs' chances with the market's.

Positive edges · 3

BetBugs probabilities

How likely BetBugs thought each outcome was.

Result1 of 1 landed

Signal quality Medium · Uncertainty band Slight lean · Not priced
The read
Siniakova has the better recent hard-court results and a clear second-set advantage, which gives her a small edge in a close match.
- Siniakova is 5-4 on hard this season and won her last two matches in straight sets.
- Siniakova has won 7 of 9 second sets on hard.
- Boulter is 6-7 on hard and 4-9 in second sets.
- Siniakova's recent hard-court game margins were +9, +7, -7, -1, +5 and -7.
BetBugs · Match WinnerwonKaterina SiniakovaEstimated chance54%

Games1 of 4 landed

Signal quality Medium · Uncertainty band Lean · Not priced
The read
Most recent first sets for both players have stayed under 10 games, and tiebreaks have been uncommon.
- Siniakova's first sets average 8.7 total games on hard.
- Siniakova's last six first sets included four under 9.5 games.
- Boulter's last six first sets included five under 9.5 games.
- Combined hard-court first-set tiebreaks: 3 in 22 matches.
BetBugs · Set 1 Total GameswonUnder 9.5Estimated chance62%
Signal quality Medium · Uncertainty band Lean · Not priced
The read
Boulter's second sets have usually been short, and second-set tiebreaks are rare in this sample.
- Boulter's second sets average 8.5 total games on hard.
- Boulter's last six second sets included five under 9.5 games.
- Siniakova's second sets average 9.1 total games on hard.
- Combined hard-court second-set tiebreaks: 1 in 22 matches.
BetBugs · Set 2 Total GameslostUnder 9.5Estimated chance60%
Signal quality Medium · Uncertainty band Lean · Market price 1.85
The read
Boulter's recent margins clear a two-and-a-half-game cushion more often than not, and Siniakova's heavy losses leave room for Boulter to stay close.
- Boulter's recent hard-court game margins were +3, +9, +8, -8, -6 and +5.
- She stayed within two games or better in four of those six matches.
- Two of her three Osaka wins came in straight sets.
- Siniakova's recent losses included margins of -7, -1 and -7.
BetBugs · Game HandicaplostKatie Boulter +2.5Estimated chance58%
Signal quality Medium · Uncertainty band Slight lean · Not priced
The read
The two players' hard-court matches sit right around the total, with Siniakova's recent matches pulling slightly higher.
- Boulter's hard-court matches average 20.6 total games.
- Siniakova's hard-court matches average 21.1 total games.
- Boulter's last six completed matches averaged 18.8 total games.
- Siniakova's last six completed matches averaged 21.7 total games.
BetBugs · Total GameslostOver 20.5Estimated chance52%

Sets3 of 3 landed

Signal quality Medium · Uncertainty band Lean · Market price 1.50
The read
Both players have more straight-set results than three-set matches on hard courts, so the under is favored.
- Siniakova has straight-set wins in four of her five hard-court victories.
- Boulter's hard-court scorelines include six 0-2 losses and three 2-0 wins.
- Combined hard-court scorelines: 8 three-set matches out of 22.
- Boulter's last three Osaka wins include two in straight sets.
BetBugs · Total SetswonUnder 2.5Estimated chance62%
Signal quality Medium · Uncertainty band Lean · Market price 1.60
The read
Siniakova's second-set record is the clearest split in the evidence and gives her a strong chance to take that set.
- Siniakova has won 7 of 9 second sets on hard this season.
- She won the second set in five of her last six matches.
- Boulter has won only 4 of 13 second sets on hard.
- Boulter's second-set game average on hard is 3.5 won to 5.0 lost.
BetBugs · Set 2 WinnerwonKaterina SiniakovaEstimated chance62%
Signal quality Medium · Uncertainty band Slight lean · Market price 1.60
The read
Siniakova has been the stronger first-set player in the recent sample, though the overall hard-court numbers are close.
- Siniakova has won 5 of 9 first sets on hard this season.
- She won the first set in four of her last six matches.
- Boulter has won 6 of 13 first sets on hard.
- Boulter lost the first set in three of her last six matches.
BetBugs · Set 1 WinnerwonKaterina SiniakovaEstimated chance54%

Match stats1 of 1 landed

Signal quality Medium · Uncertainty band Strong lean · Not priced
The read
The combined hard-court and recent records show tiebreaks are uncommon, so no is favored.
- Siniakova has had one tiebreak in nine hard-court matches.
- Boulter has had three tiebreaks in 13 hard-court matches.
- Combined hard-court rate is 4 of 22 matches.
- Recent matches: one tiebreak in 12 completed matches between them.
BetBugs · Tiebreak in MatchwonNoEstimated chance78%

Prediction history

Katerina Siniakova: 3/6 recent winner projections matched

3 of 6 comparable winner projections favouring Katerina Siniakova matched the recorded result. This is a limited recent sample, not a guarantee for this match.

Recent evidence for Katerina Siniakova6 matches

Date / competitionMatch resultPredictedActualResult

1 Jul·WTA Wimbledon

#36Katerina Siniakova0-2#48Nikola Bartunkova

BetBugsKaterina Siniakova to win·58%

Missed

1 Jul 2026

WTA Wimbledon

#36Katerina Siniakova0-2#48Nikola Bartunkova

Katerina Siniakova to win

58%probability

Nikola Bartunkova won

Missed

29 Jun·WTA Wimbledon

#34Katerina Siniakova2-0#153Qinwen Zheng

BetBugsKaterina Siniakova to win·72%

Matched

29 Jun 2026

WTA Wimbledon

#34Katerina Siniakova2-0#153Qinwen Zheng

Katerina Siniakova to win

72%probability

Katerina Siniakova won

Matched

21 Jun·WTA Bad Homburg

#37Liudmila Samsonova2-0#34Katerina Siniakova

BetBugsKaterina Siniakova to win·58%

Missed

21 Jun 2026

WTA Bad Homburg

#37Liudmila Samsonova2-0#34Katerina Siniakova

Katerina Siniakova to win

58%probability

Liudmila Samsonova won

Missed

26 May·WTA Roland Garros

#93Simona Waltert0-2#36Katerina Siniakova

BetBugsKaterina Siniakova to win·65%

Matched

26 May 2026

WTA Roland Garros

#93Simona Waltert0-2#36Katerina Siniakova

Katerina Siniakova to win

65%probability

Katerina Siniakova won

Matched

6 May·WTA Rome

#39Katerina Siniakova2-0#43Lois Boisson

BetBugsKaterina Siniakova to win·65%

Matched

6 May 2026

WTA Rome

#39Katerina Siniakova2-0#43Lois Boisson

Katerina Siniakova to win

65%probability

Katerina Siniakova won

Matched

Head-to-Head

1-0 (1 meetings)

W4-6 6-2 6-1Katie Boulter#58vKaterina Siniakova#86Apr 22, 2025

1 total meetings

Previous match context available

Katie Boulter

6W 9L

3-6 6-3 6-3#91Antonia Ruzic

6-2 6-1#82Viktorija Golubic

6-3 6-1#115Himeno Sakatsume

6-3 6-1#13Diana Shnaider

7-6(3) 6-1#7Karolina Muchova

6-3 6-4#168Mai Hontama

6-2 7-6(3)#8Linda Noskova

6-1 6-0#7Karolina Muchova

6-4 3-6 6-0#161Carol Young Suh Lee

6-3 6-3#8Linda Noskova

7-5 0-6 6-4#73Katie Volynets

7-6(3) 7-5#186Kayla Cross

3-6 6-2 6-2#55Ashlyn Krueger

6-4 6-2#152Tyra Caterina Grant

6-7(5) 6-3 6-3#30Leylah Annie Fernandez

Katerina Siniakova

7W 8L

6-1 6-2#114Mary Stoiana

6-4 6-1#77Magda Linette

6-4 0-6 4-0 ret.#37Peyton Stearns

6-1 5-7 6-2#43Liudmila Samsonova

1-6 6-4 6-2#6Elina Svitolina

6-4 6-3#77Magda Linette

6-2 5-7 6-1#19Naomi Osaka

6-3 6-2#65Elisabetta Cocciaretto

6-1 6-3#21Madison Keys

6-7(5) 6-1 6-1#96Jessica Bouzas Maneiro

6-7(1) 6-0 5-2 ret.#67Kamilla Rakhimova

6-2 6-4#29Nikola Bartunkova

6-4 6-4#22Qinwen Zheng

6-3 7-5#43Liudmila Samsonova

6-2 6-4#4Jessica Pegula

Stat Battle

Last 15 match performance, compared side by side.

KBKatie BoulterBoulter

Last 15

0–5

9 core stats · 4 even

Katerina SiniakovaSiniakovaKS

Katerina Siniakova carries the stronger recent form — Katie Boulter's route runs through 1st serve in.

Serve · 0–3 · 2 even

1st Serve In14/15 · 15/1558.5%—58.5%

1st Serve Won14/15 · 15/1563.5%—63.4%

2nd Serve Won14/15 · 15/1541.0%+5.4pp46.4%

Aces / Match14/15 · 15/151.9+0.62.5

Double Faults / Match14/15 · 15/156.91.2 fewer5.7

Return · 0–0 · 1 even

Return Pts Won14/15 · 15/1542.3%—42.6%

Pressure · 0–1 · 1 even

Break Pts Converted14/15 · 15/1542.9%—43.5%

Break Pts Saved14/15 · 15/1550.9%+5.9pp56.8%

Points · 0–1

Total Pts Won14/15 · 15/1548.2%+1.3pp49.5%

Serve · 0–3 · 2 even

58.5%1st Serve In14/15 · 15/15—58.5%

63.5%1st Serve Won14/15 · 15/15—63.4%

41.0%2nd Serve Won14/15 · 15/15+5.4pp46.4%

1.9Aces / Match14/15 · 15/15+0.62.5

6.9Double Faults / Match14/15 · 15/151.2 fewer5.7

Return · 0–0 · 1 even

42.3%Return Pts Won14/15 · 15/15—42.6%

Pressure · 0–1 · 1 even

42.9%Break Pts Converted14/15 · 15/15—43.5%

50.9%Break Pts Saved14/15 · 15/15+5.9pp56.8%

Points · 0–1

48.2%Total Pts Won14/15 · 15/15+1.3pp49.5%

Katie Boulter #58United Kingdom0Katerina Siniakova #86Czechia2

Player Profiles

Katie Boulter

Katerina Siniakova

Quick Take

Context

BetBugs edges

Katie Boulter +2.5

Under 20.5

Katie Boulter

Katerina Siniakova

Under 2.5

Katerina Siniakova

Katerina Siniakova 2-0

BetBugs probabilities

Result1 of 1 landed

Games1 of 4 landed

Sets3 of 3 landed

Match stats1 of 1 landed

Katerina Siniakova: 3/6 recent winner projections matched

Head-to-Head

Katie Boulter

Katerina Siniakova

Stat Battle