MexicoWTA GuadalajaraFinished

Predictions graded

Marta Kostyuk #11Ukraine1Liudmila Samsonova #55Russia2

Sets 6-4 · 2-6 · 5-7Fri 18 Sept 2026, 00:25 Predictions gradedQuarter-FinalHard

Predictions3–443%

Edges5–363%

Player Profiles

Ranking advantageMarta Kostyuk · 44 places

Marta Kostyuk

Ukraine

Born 28 June 2002. She reached a career-high singles ranking of No. 11 in July 2026.

Current ranking: #11
Peak ranking: #11 · 2026
Current age: 24
Preferred surface: —
Hand: Right handed
Height: 175 cm

Liudmila Samsonova

Russia

Current WTA ranking No. 55; career high No. 12 reached in February 2023. She is right-handed, 182 cm tall and identifies hard court as her favorite surface.

Current ranking: #55
Peak ranking: #12 · 2023
Current age: 27
Preferred surface: Hard
Hand: Right handed
Height: 182 cm

Quick Take

Pre-match view

Context last updated 17 Sep 2026, 22:06 · Europe/Bucharest

Kostyuk owns the better hard-court form and a fresher body, but Samsonova's 4-0 head-to-head and break-point resilience make the 4.00 underdog price the value side.

The strongest edges sit in the totals — Over 21.5 games (+14.5pts) and Over 2.5 sets (+16.5pts) — while Kostyuk's short 1.25/1.30 quotes and the -4.5 handicap are best avoided.

Context

Kostyuk, 24, is the No. 10 player in this matchup and reached a career-high ranking in 2026. Samsonova, 27, is ranked No. 50 and stands 182 cm, giving her a taller serving profile than the 175 cm Kostyuk.
The head-to-head is the strongest single piece of evidence in this matchup. Samsonova won their 2023 hard-court meeting 6-4 6-2 and their 2023 clay meeting 6-4 6-7(4) 7-5, plus two earlier hard-court wins in 2020. In those four matches Samsonova won 74% of first-serve points compared with Kostyuk's 61%, and Kostyuk double-faulted 37 times across the series. The sample is small and dates back to 2023, so it is a pattern rather than a current guarantee.
- Samsonova leads the head-to-head 4-0, with three wins on hard courts and one on clay.
- Their most recent meeting was a 6-4 6-7(4) 7-5 Samsonova win in October 2023.
- In the four meetings Samsonova won 74% of first-serve points; Kostyuk won 61%.
- Kostyuk double-faulted 37 times across the four matches, compared with 22 for Samsonova.
Kostyuk, 23, is the WTA No. 10 and the right-hander in this quarter-final. She attended to her wrist during her US Open fourth-round match on 6 September, and her Guadalajara second-round match became a walkover when Taylor Townsend withdrew.
Because that walkover means she has not completed a match in Guadalajara, there is no newer on-court update on the wrist. If the issue is still active, it can limit her serving and her tolerance for repeated groundstrokes, which matters most in a long, physical match. The stored recent sample of three wins from five tracked matches gives no clear signal either way.
- Kostyuk flexed and rubbed the wrist that had troubled her during the 6 September US Open match.
- Kostyuk advanced in Guadalajara after Taylor Townsend withdrew before their second-round match.
- Stored recent sample: 3 wins from 5 tracked matches.
To watchSources checked 17 Sep 2026, 22:05 · Europe/BucharestNoskova survives Kostyuk scare to reach QFs at the 2026 US Openwww.usopen.org · 6 Sep 2026
Kostyuk is the higher-ranked player at No. 10 and has played most of her recent tennis on hard courts. Samsonova sits at No. 50 and has a more mixed hard-court record in 2026.
In the last 15 matches on hard courts Kostyuk is 8-3 with 57.3% of games won, 73% of first-serve points won and 46.2% of return points won. Samsonova is 8-4 on the surface with 52.1% of games won, 72.7% of first-serve points won and 40.5% of return points won. Samsonova has saved 64.5% of break points on hard courts against Kostyuk's 60%, so Kostyuk's edge is not uniform across every serve metric.
- Kostyuk is 8-3 on hard courts in her last 15 matches; Samsonova is 8-4.
- Kostyuk has won 57.3% of hard-court games in that window; Samsonova has won 52.1%.
- Kostyuk has won 46.2% of hard-court return points; Samsonova has won 40.5%.
- Samsonova has saved 64.5% of hard-court break points; Kostyuk has saved 60%.
Samsonova is 27 and ranked No. 50. She has played a heavy recent schedule, with several three-set matches on hard courts in September 2026.
Samsonova's last two matches in Guadalajara both went the distance, and her 132.2-minute average across the last 15 matches is the highest workload cue in this matchup. Kostyuk's average is 93.6 minutes, so she has spent considerably less time on court. That gap could matter in a best-of-three quarter-final if the match goes long, though Samsonova has shown she can win tight sets.
- Samsonova's average match duration in the last 15 is 132.2 minutes; Kostyuk's is 93.6 minutes.
- Samsonova beat Kayla Day 7-6(4) 2-6 7-6(5) in her most recent match.
- Samsonova also went three sets against Elsa Jacquemot in the previous round.
- Three of Samsonova's last five matches have gone to a deciding set.

BetBugs edges

Compare BetBugs' chances with the market's.

Positive edges · 5

BetBugs probabilities

How likely BetBugs thought each outcome was.

Result0 of 1 landed

Signal quality Medium · Uncertainty band Lean · Market price 1.25
The read
Kostyuk's stronger hard-court serve/return structure and superior games-won profile (57.3% vs 52.1% on hard) outweigh Samsonova's 4-0 head-to-head, which is entirely from 2020-2023 and predates the current form window.
- Kostyuk last-15 overall: 11-4 (73.3%) with 24 of 35 sets won; hard-court split 8-3 (72.7%) across 11 tracked matches.
- Kostyuk hard-court serve/return window: 73.0% first-serve points won, 46.2% return points won, 57.0% break points converted (11 matches).
- Samsonova last-15: 10-5 (66.7%) but only 52.8% games won and 41.3% return points won; hard-court return points won just 40.5% (11 matches).
- Samsonova's Guadalajara QF run cost 2h47m in a deciding-set tie-break on 16 September, while Kostyuk has not completed a match at this event.
BetBugs · Match WinnerlostMarta KostyukEstimated chance62%

Games1 of 1 landed

Signal quality Medium · Uncertainty band Lean · Market price 2.20
The read
Samsonova's high double-fault rate, poor break-point conversion and long recent match durations point to extended sets, while Kostyuk's hard-court games-won rate is not dominant enough to force a quick straight-sets finish.
- Samsonova's last 5 matches include three 3-setters and two tie-break sets; her Guadalajara R16 lasted 2h47m.
- Samsonova last-15 average match duration 132.2 minutes (14 matches) vs Kostyuk 93.6 minutes (15 matches).
- Samsonova double-faults 5.9 per match (14 matches) and converts only 40.2% of break points, extending sets.
- Kostyuk's last-15 hard matches average 97.2 minutes with 57.3% games won, indicating competitive but not blowout sets.
BetBugs · Total GameswonOver 21.5Estimated chance60%

Sets2 of 3 landed

Signal quality Medium · Uncertainty band Lean · Market price 1.30
The read
Kostyuk's higher first-set conversion and cleaner hard-court set/game numbers give her the early edge, while Samsonova's low first-serve percentage and heavy recent court time raise her risk of a slow opening set.
- Kostyuk career first-set win conversion 88% vs Samsonova 84%.
- Kostyuk last-15 hard: 69.2% sets won (18/26) and 57.3% games won across 11 matches.
- Samsonova has needed deciding sets in 3 of her last 5 matches, including two tie-break first sets in Guadalajara.
- Samsonova's 51.9% first-serve-in rate (14 matches) leaves her second serve exposed early.
BetBugs · Set 1 WinnerwonMarta KostyukEstimated chance58%
Signal quality Medium · Uncertainty band Slight lean · Market price 2.60
The read
Both players' recent windows show frequent set losses and deciding-set exposure, and Samsonova's strong break-point saving gives her a realistic path to taking one set.
- Samsonova has gone to a deciding set in 3 of her last 5 matches (Guadalajara R16 and R32 included).
- Samsonova last-15 sets won 61.5% (24/39) — she drops sets regularly despite winning matches.
- Kostyuk last-15 sets won 68.6% (24/35), but her two most recent losses came in three sets.
- Samsonova's 65.7% break-point save rate (13 matches) helps her steal a set even when outplayed.
BetBugs · Total SetswonOver 2.5Estimated chance55%
Signal quality Low · Uncertainty band Slight lean · Market price 1.30
The read
Kostyuk's higher hard-court set-win rate and Samsonova's pattern of dropping second sets in recent matches give Kostyuk the edge in set two.
- Kostyuk last-15 hard: 69.2% sets won (18/26) across 11 matches.
- Samsonova last-15 hard: 61.3% sets won (19/31) across 12 matches.
- Samsonova has lost the second set in 3 of her last 5 matches (vs Day, Jacquemot, Joint).
- Kostyuk's 46.2% hard-court return points won gives her sustained pressure across sets.
BetBugs · Set 2 WinnerlostMarta KostyukEstimated chance55%

Match stats0 of 0 landed

Signal quality Medium · Uncertainty band Lean · Not priced
The read
Samsonova's high double-fault rate combined with Kostyuk's moderate rate pushes the combined total comfortably above 8.5, supported by Samsonova's low first-serve percentage.
- Samsonova last-15: 5.9 double faults per match (83 in 14 matches); hard-court split 6.3 per match (69 in 11).
- Kostyuk last-15: 4.0 double faults per match (60 in 15 matches); hard-court split 4.7 per match (52 in 11).
- Combined hard-court double-fault rate of roughly 11 per match.
- Samsonova's 51.9% first-serve-in rate (14 matches) forces extra second serves.
BetBugs · Total Double Faultsnot gradableOver 8.5Estimated chance58%
Signal quality Medium · Uncertainty band Slight lean · Not priced
The read
Samsonova's Guadalajara run has been tie-break heavy and her hard-court games-won rate is near even, making at least one tie-break in the match more likely than not.
- Samsonova's last two Guadalajara matches produced four tie-break sets combined (7-6(4), 7-6(5), 7-6(6)).
- Samsonova last-15 hard: 52.1% games won, indicating tight sets rather than blowouts.
- Kostyuk's recent hard-court matches include a 7-6(4) set vs Katherine Sebov on 4 August.
- Both players' break-point conversion rates (Kostyuk 57.0%, Samsonova 42.2% on hard) suggest holds dominate.
BetBugs · Tiebreak in Matchnot gradableYesEstimated chance55%
Signal quality Low · Uncertainty band Slight lean · Not priced
The read
Both players' hard-court ace rates combine to just under ten per match, so a line of 8.5 sits near the expected value with a slight lean to the over.
- Kostyuk last-15 hard: 5.5 aces per match (61 aces in 11 matches).
- Samsonova last-15 hard: 4.2 aces per match (46 aces in 11 matches).
- Combined hard-court ace rate of roughly 9.7 per match across the tracked windows.
- Samsonova's 182cm frame and 4.4 aces per match overall (14 matches) support a serve-driven total.
BetBugs · Total Acesnot gradableOver 8.5Estimated chance52%

Prediction history

Marta Kostyuk has been highly reliable when projected to win, fulfilling 13 of 15 recent match-winner projections

Marta Kostyuk fulfilled 13 of 15 match-winner projections, with an average estimated probability of 70.1% against an expected 10.5 fulfilled predictions. Her two missed projections both ended in straight-set losses, and those misses carried a lower average estimated probability of 56.5% compared with 72.2% for matched projections. The current 62% projection sits within her historical range of 55% to 88%, and her recent evidence shows a strong overall conversion record.

Recent evidence for Marta Kostyuk15 matches

Date / competitionMatch resultPredictedActualResult

9 Jul·WTA Wimbledon

#13Marta Kostyuk0-2#12Linda Noskova

BetBugsMarta Kostyuk to win·58%

Missed

9 Jul 2026

WTA Wimbledon

#13Marta Kostyuk0-2#12Linda Noskova

Marta Kostyuk to win

58%probability

Linda Noskova won

Missed

8 Jul·WTA Wimbledon

#13Marta Kostyuk2-0#17Jasmine Paolini

BetBugsMarta Kostyuk to win·58%

Matched

8 Jul 2026

WTA Wimbledon

#13Marta Kostyuk2-0#17Jasmine Paolini

Marta Kostyuk to win

58%probability

Marta Kostyuk won

Matched

6 Jul·WTA Wimbledon

#102Ashlyn Krueger0-2#13Marta Kostyuk

BetBugsMarta Kostyuk to win·62%

Matched

6 Jul 2026

WTA Wimbledon

#102Ashlyn Krueger0-2#13Marta Kostyuk

Marta Kostyuk to win

62%probability

Marta Kostyuk won

Matched

2 Jul·WTA Wimbledon

#114Anna Blinkova1-2#13Marta Kostyuk

BetBugsMarta Kostyuk to win·78%

Matched

2 Jul 2026

WTA Wimbledon

#114Anna Blinkova1-2#13Marta Kostyuk

Marta Kostyuk to win

78%probability

Marta Kostyuk won

Matched

30 Jun·WTA Wimbledon

#594Nadia Podoroska0-2#13Marta Kostyuk

BetBugsMarta Kostyuk to win·85%

Matched

30 Jun 2026

WTA Wimbledon

#594Nadia Podoroska0-2#13Marta Kostyuk

Marta Kostyuk to win

85%probability

Marta Kostyuk won

Matched

Head-to-Head

0-4 (4 meetings)

L6-4 6-7(4) 7-5Marta Kostyuk#10vLiudmila Samsonova#50Oct 4, 2023

L6-4 6-2Marta Kostyuk#10vLiudmila Samsonova#50Aug 4, 2023

L4-6 6-4 6-3Marta Kostyuk#10vLiudmila Samsonova#50Aug 2, 2020

L7-6(4) 6-4Marta Kostyuk#10vLiudmila Samsonova#50Jan 6, 2020

Liudmila Samsonova dominates (4 meetings)4 total meetings

Previous match context available

Marta Kostyuk

11W 4L

7-5 5-7 6-4#6Linda Noskova

6-3 6-2#21Ekaterina Alexandrova

6-1 7-5#169Sloane Stephens

6-4 6-1#175Storm Hunter

6-2 6-2#4Cori Gauff

4-6 6-0 6-2#5Mirra Andreeva

7-5 7-5#169Sloane Stephens

4-6 6-3 7-5#100Sofia Kenin

3-6 6-1 6-2#9Iga Swiatek

6-3 6-1#23Madison Keys

7-6(4) 6-0#214Katherine Sebov

6-4 6-4#6Linda Noskova

6-3 6-2#20Jasmine Paolini

6-4 6-4#71Ashlyn Krueger

6-2 4-6 6-1#24Emma Navarro

Liudmila Samsonova

10W 5L

7-6(4) 2-6 7-6(5)#123Kayla Day

7-6(6) 6-2#156Elsa Jacquemot

3-6 6-2 6-2#68Maya Joint

2-6 6-4 6-1#4Cori Gauff

7-6(5) 5-7 7-5#78Yulia Putintseva

6-4 4-6 6-4#1Elena Rybakina

7-5 6-7(3) 6-2#68Maya Joint

6-1 7-5#38Barbora Krejcikova

7-6(9) 7-5#51Janice Tjen

6-3 6-4#13Diana Shnaider

6-2 6-2#40Xinyu Wang

3-6 6-4 6-4#23Madison Keys

4-6 7-6(3) 6-4#27Marie Bouzkova

6-4 4-6 6-2#13Diana Shnaider

6-3 6-3#103Polina Kudermetova

Stat Battle

Last 15 match performance, compared side by side.

MKMarta KostyukKostyuk

Last 15

7–1

9 core stats · 1 even

Liudmila SamsonovaSamsonovaLS

Marta Kostyuk carries the stronger recent form — Liudmila Samsonova's route runs through pressure.

Serve · 4–0 · 1 even

1st Serve In15/15 · 14/1554.5%+2.6pp51.9%

1st Serve Won15/15 · 14/1573.5%—73.3%

2nd Serve Won15/15 · 14/1547.8%+1.9pp45.9%

Aces / Match15/15 · 14/154.9+0.54.4

Double Faults / Match15/15 · 14/154.01.9 fewer5.9

Return · 1–0

Return Pts Won15/15 · 14/1545.2%+3.9pp41.3%

Pressure · 1–1

Break Pts Converted15/15 · 13/1554.4%+14.2pp40.2%

Break Pts Saved15/15 · 13/1559.2%+6.5pp65.7%

Points · 1–0

Total Pts Won15/15 · 14/1553.4%+2.5pp50.9%

Serve · 4–0 · 1 even

54.5%1st Serve In15/15 · 14/15+2.6pp51.9%

73.5%1st Serve Won15/15 · 14/15—73.3%

47.8%2nd Serve Won15/15 · 14/15+1.9pp45.9%

4.9Aces / Match15/15 · 14/15+0.54.4

4.0Double Faults / Match15/15 · 14/151.9 fewer5.9

Return · 1–0

45.2%Return Pts Won15/15 · 14/15+3.9pp41.3%

Pressure · 1–1

54.4%Break Pts Converted15/15 · 13/15+14.2pp40.2%

59.2%Break Pts Saved15/15 · 13/15+6.5pp65.7%

Points · 1–0

53.4%Total Pts Won15/15 · 14/15+2.5pp50.9%

Marta Kostyuk #11Ukraine1Liudmila Samsonova #55Russia2

Player Profiles

Marta Kostyuk

Liudmila Samsonova

Quick Take

Context

BetBugs edges

Over 21.5

Over 2.5

Over 9.5

Over 9.5

Liudmila Samsonova

Marta Kostyuk

Marta Kostyuk

Marta Kostyuk

BetBugs probabilities

Result0 of 1 landed

Games1 of 1 landed

Sets2 of 3 landed

Match stats0 of 0 landed

Marta Kostyuk has been highly reliable when projected to win, fulfilling 13 of 15 recent match-winner projections

Head-to-Head

Marta Kostyuk

Liudmila Samsonova

Stat Battle