Marta Kostyuk vs. Sloane Stephens — US Open 2026 Second-Round Match Report
Sloane Stephens has spent much of 2026 climbing back toward a part of the rankings where her name looks more familiar.
Marta Kostyuk has now stopped her twice in three weeks.
The No. 11 seed followed her 7-5, 7-5 victory over Stephens in Cincinnati with a 6-1, 7-5 win at the US Open, ending the former champion’s New York run just when the second set appeared capable of becoming considerably more complicated.
Stephens had a set point at 5-4.
She never reached 6-4.
The Ukrainian saved it, won the final three games and moved into the third round with a performance in which the gap between the two was far larger than the second-set score alone suggests.
Kostyuk Has the First Set Almost Entirely to Herself
Kostyuk established the terms immediately.
She held the opening game, broke Stephens for 2-0 and consolidated for 3-0.
Stephens finally got herself on the board at 3-1, but there was no change in direction. Kostyuk held for 4-1 and then struck again on return.
Another break made it 5-1.
The Ukrainian served out the set in the following game.
6-1.
Stephens had been given almost no foothold. Kostyuk was not broken, created the two breaks she needed and allowed the opening set to disappear before the American could properly establish herself.
Set 1 at a Glance
- Kostyuk won 30 of 49 total points, hitting 13 winners to Stephens’ 3.
- Kostyuk won her return games 2 of 3, while Stephens failed to win any (0 of 4).
- Kostyuk won her service games at a perfect 4 of 4, while Stephens managed 1 of 3.
Full Set 1 Stats
| Kostyuk | Statistic | Stephens |
|---|---|---|
| Set 1 Duration: 0h30m | ||
| 1.64 | Dominance Ratio | 0.61 |
| 13 | Winners | 3 |
| 9 | Unforced Errors | 7 |
| 284 | Serve Rating | 196 |
| 2 | Aces | 0 |
| 3 | Double Faults | 1 |
| 56% (15/27) | 1st Serve % | 77% (17/22) |
| 87% (13/15) | 1st Serve Points Won | 47% (8/17) |
| 42% (5/12) | 2nd Serve Points Won | 40% (2/5) |
| 100% (1/1) | Break Points Saved | 67% (4/6) |
| 213 | Return Rating | 71 |
| 53% (9/17) | 1st Return Points Won | 13% (2/15) |
| 60% (3/5) | 2nd Return Points Won | 58% (7/12) |
| 2/6 | Break Points Won | 0/1 |
| 30 | Total Points Won | 19 |
Stephens Gets Her Chance at 5-4
The second set was a different contest.
Stephens held to begin and stayed in front through 2-1 before Kostyuk broke for 3-2.
This time Stephens answered.
After Kostyuk consolidated for 4-2 and Stephens held for 4-3, the American broke back to level at 4-4.
Then came her best opportunity of the match.
Stephens held for 5-4 and pushed Kostyuk to 30-40 in the next game.
Set point.
A deciding set was one point away.
Kostyuk erased it.
She eventually held for 5-5, broke Stephens immediately afterwards for 6-5 and then served out the match.
Three consecutive games transformed 4-5 into 7-5.
Stephens had finally forced Kostyuk into danger.
Kostyuk was out of it before another set could begin.
Set 2 at a Glance
- Kostyuk hit 6 aces to Stephens’ 0, and didn’t commit a single double fault (0) compared with Stephens’ 1.
- Kostyuk won 8 of 13 pressure points, well ahead of Stephens’ 5 of 13.
- Kostyuk won 43 of 81 total points, hitting 17 winners to Stephens’ 7.
Full Set 2 Stats
| Kostyuk | Statistic | Stephens |
|---|---|---|
| Set 2 Duration: 0h57m | ||
| 1.20 | Dominance Ratio | 0.83 |
| 17 | Winners | 7 |
| 18 | Unforced Errors | 13 |
| 268 | Serve Rating | 244 |
| 6 | Aces | 0 |
| 0 | Double Faults | 1 |
| 55% (21/38) | 1st Serve % | 74% (32/43) |
| 71% (15/21) | 1st Serve Points Won | 59% (19/32) |
| 53% (9/17) | 2nd Serve Points Won | 45% (5/11) |
| 67% (2/3) | Break Points Saved | 50% (2/4) |
| 179 | Return Rating | 126 |
| 41% (13/32) | 1st Return Points Won | 29% (6/21) |
| 55% (6/11) | 2nd Return Points Won | 47% (8/17) |
| 2/4 | Break Points Won | 1/3 |
| 43 | Total Points Won | 38 |
Thirty Winners Tell More of the Story Than 7-5 Does
The second set became competitive, but the full-match statistics show how much more damage Kostyuk was producing.
She struck 30 winners to Stephens’ 10.
Kostyuk also served eight aces while Stephens did not hit one, and although the Ukrainian landed only 55 percent of her first serves, she won an imposing 78 percent of the points behind them.
Stephens put 75 percent of her first serves into play but won only 55 percent of those points.
That distinction was important. Getting the first serve in was not enough when Kostyuk was still winning almost half of the return points behind it.
Kostyuk finished with four breaks of serve from 10 opportunities. Stephens managed one from four.
The No. 11 seed won 73 of the 130 points, produced a 1.35 dominance ratio and held in nine of her 10 service games.
Even with 27 unforced errors, Kostyuk’s 30 winners gave the match an attacking imbalance Stephens could not consistently overturn.
Stephens Has Travelled a Long Way From No. 1102
This US Open defeat lands very differently when placed against Stephens’ 2026 season.
She began the year ranked No. 1102 when she came through Australian Open qualifying. By Indian Wells she was No. 780, by the end of March No. 554 and by late April No. 396. The climb continued through the summer, reaching No. 320 in late July and No. 208 shortly before the US Open. She entered this match at No. 209.
That rise has required Stephens to operate in places far removed from the stage on which she once became a Grand Slam champion.
She played qualifying at both the Australian Open and Roland Garros. And she appeared at WTA 125 and ITF-level events. Moreover, she needed wildcards at several bigger tournaments.
There have also been signs that the old level can still appear.
Stephens defeated Diane Parry in Madrid qualifying, Tatjana Maria in Linz, Anastasia Potapova in Cincinnati and, most recently, No. 38 Clara Tauson 6-4, 6-1 in the opening round here in New York.
For a player who was outside the Top 1000 in January, returning to the US Open and winning a main-draw match is not a negligible piece of progress.
Especially here.
Stephens remains the 2017 US Open champion, one of three former Grand Slam champions to receive a women’s singles wildcard for this year’s tournament.
Sloane Stephens’ WTA Ranking Rise in 2026
The direction is unmistakable:
The final little plateau should not obscure the scale of the climb.
Stephens has recovered almost 900 ranking positions since January.
Kostyuk Is Now One Win From the Second Week
Kostyuk’s side of the draw is beginning to take shape.
Her first-round opponent was qualifier Storm Hunter, whom she beat 6-4, 6-1. Stephens then occupied the next line of the bracket after beating Clara Tauson. RallyHer’s original draw places the winner of this second-round match against the survivor from the adjacent pairing built from Kimberly Birrell and No. 18 seed Ekaterina Alexandrova.
That means Kostyuk’s next opponent will be Birrell or Alexandrova, with a place in the last 16 available to the winner.
There is another useful piece of context here.
Kostyuk already beat Stephens in Cincinnati only weeks ago, 7-5, 7-5.
This time the first set was much easier.
The second nearly became much harder.
Stephens’ Climb Continues, but Kostyuk Keeps Moving
For Stephens, the US Open ends in the second round.
For her season, that is not the same thing as going backwards.
A player who started 2026 at No. 1102 has qualified for two Grand Slams, worked her way through lower-level tournaments, returned to the main tour and beaten a Top-40 opponent at the Slam she won nine years ago.
There is still distance between that version of Stephens and the player who lifted the trophy here in 2017.
There is considerably less distance than there was in January.
Kostyuk, meanwhile, has no reason to look backwards.
She has beaten Stephens twice in three weeks, is into the US Open third round and now sits one victory away from the second week in New York.
This time, when Stephens finally found the opening at 5-4, Kostyuk closed it herself.