Kostyuk vs Stephens Prediction 2 September 2026
🔊 Marta Kostyuk and Sloane Stephens meet in the second round of the US Open in a match that would have looked very different eight years ago. Stephens won this tournament in 2017, beating Madison Keys 6-3, 6-0 in the final, reached a career-high ranking of third in the world and played in the Roland Garros final. She is now ranked 209th. Kostyuk is moving in the opposite direction: in July she rose to 11th, her career high, and in Cincinnati she beat the world number five.
Head-to-Head
📊 The two players have met once, and very recently: on 18 August in Cincinnati, Kostyuk won 7-5, 7-5. Both sets reached 5-5, and the match produced 24 games in total - despite Kostyuk being the heavy favourite.
Marta Kostyuk Player Overview
Kostyuk came through the first round comfortably, beating Storm Hunter 6-4, 6-1. More telling was her run in Cincinnati in August: she beat Sofia Kenin (4-6, 6-3, 7-5), Sloane Stephens and Mirra Andreeva (4-6, 6-0, 6-2) - the world No. 5 - before only Coco Gauff could stop her. On 13 July, Kostyuk reached a career-high ranking of No. 11.
On hard courts this season she has gone 11-6. Her serve carries real weight - 6% aces and 72% of first-serve points won, a top-10-level figure - but her first serve goes in only 57% of the time, and she double-faults on 8% of her service points, which is high for a player of her calibre. Her return points won stand at 44%. That combination shapes her matches: the ball-striking is there, but she struggles to control the scoreboard.
Match Results: Marta Kostyuk
Sloane Stephens Player Overview
Stephens opened her campaign with a result few would expect from the world No. 209: a 6-4, 6-1 win over Clara Tauson, a top-50 opponent. That followed a victory on 16 August over Anastasia Potapova, ranked 25th. Between those two wins, however, she lost on 24 August in Philadelphia to Mananchaya Sawangkaew, ranked 97th, after taking the first set.
Her hard-court season is balanced but modest: nine wins and nine losses. Her serve offers very little - just 2% aces - though she also double-faults rarely at 3%, and lands her first serve 66% of the time. Her return game carries her, winning 44% of points on return. One further detail: her serve has not improved through August and September - her first-serve percentage is actually lower than it was in the first half of the season. Her results have gone up; her game has not.
Match Results: Sloane Stephens
Key factors
- On 18 August in Cincinnati, Kostyuk beat Stephens 7-5, 7-5.
- Kostyuk lands her first serve in only 57% of points and double-faults on 8% of her service points.
- Against opponents who hit 2-4% aces, Kostyuk wins by a margin of six or more games in 6 of 15 matches.
- Stephens double-faults on just 3% of her service points.
- In the first round, Stephens beat a top-50 opponent 6-4, 6-1.
Expected scenario
Kostyuk is stronger in most aspects of shot-making, but her serve is the most vulnerable element in this matchup. With a 57% first-serve percentage, she gives her opponent a large number of second serves to attack, and Stephens is precisely the kind of player who thrives on returning and extended rallies. Add an 8% double-fault rate, and Kostyuk is handing away some games without her opponent having to do anything.
Stephens faces the opposite challenge. Her serve carries no real threat, but she makes very few errors on the second serve and holds through consistency. Against her, you have to win points rather than wait for mistakes, and that is exactly where Kostyuk tends to struggle in the closing stages. Their August match followed this pattern precisely: the Ukrainian was the better player from the opening game, yet both sets went to 5-5.
Total Games Prediction
The total points in the same direction for the same reason: both players win points on return and both struggle to hold serve in the closing stages. Against opponents with weak serves, 10 of Kostyuk's last 15 matches over the past year and a half went over 18.5 games; Stephens has 11 of 18 this season. But the total captures the same scenario less precisely - it also goes up when the favourite pulls clear on the scoreboard simply by playing an extra set.
⭐ Editor's Prediction
The class gap is not in question: Kostyuk is ranked 11th, has beaten players from the top five, and is a deserved favourite. The only question is by how much. Fifteen days ago these two played on the same surface, and the Ukrainian controlled the match throughout - yet finished it with a margin of four games, because both sets went to 5-5.
That comes down to the matchup rather than chance. Kostyuk wins through her groundstrokes but lands just over half her first serves and makes frequent errors on the second, while Stephens is a returner with a reliable second-serve return who drags those games out to the last point. Against opponents without a strong serve, the Ukrainian wins by six games or more in only 6 of her last 15 matches. The main risk to the bet is that the American may be physically drained after her win over Townsend, though a week earlier she played three full sets in Philadelphia.
Pick: Sloane Stephens - Games Handicap +5.5.
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Betting Tips: Marta Kostyuk - Sloane Stephens
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