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Sports · US Open 2026 · Women's Singles · Round of 64
Naomi Osaka vs 
Katerina Siniakova
Round of 64
Watch: ESPN · ESPN2 · ABC · ESPN app
My pick: Naomi Osaka to advance · locked 2026-09-01 09:45 UTCPrediction
Osaka leads this 2-1 and won the last one 6-3 6-2, but Monday's evidence cuts both ways. She needed two tiebreaks and two hours two minutes to beat the world No. 101 Anastasia Zakharova, was broken serving for the first set, and was a point from 5-6 down in the second before winning four straight and taking the breaker 7-3. Ten of her eleven aces came in that second set, which is the version of her that wins this tournament. Siniakova beat Elisabetta Cocciaretto 6-3 6-2 in far less time and far less trouble. She is one of the great doubles players of the era and a far better mover than her singles ranking of 42 suggests, but her best US Open singles run is a third round eight years ago, and the two-time champion here has cleared the first round nine times in ten. The case for the upset is a first serve that landed only half the time on Monday.
The case for Naomi Osaka
70% to winTwo US Open titles, a semi-final last year, and a 2-1 record against Siniakova including a straight-sets win at Wimbledon last summer. Osaka has ten Grand Slam match wins already in 2026 — her first double-figure major season since 2019 — and eleven aces in a first-round match is a serve doing exactly what it needs to. Siniakova has been past the second round here once in her career.
The case for Katerina Siniakova
30% to winSiniakova took ninety minutes less than Osaka to reach this round and did not face a tiebreak. She has beaten Osaka before, on clay at Roland Garros in 2019, and her return game is the part of this match Osaka's numbers are most exposed to: 51% first serves in on Monday, and four breaks conceded from seven chances. A player who has won ten Grand Slam doubles titles reads a serve better than most.
Both cases written 2026-09-01, before the first ball — frozen into the record exactly as written, whatever the result. The percentages are mine — opinions with a percent sign on. They add to 100 because tennis has no draw to hide the rounding in.
Tale of the tape
Naomi OsakaKaterina SiniakovaPlayer vitals: US Open official player feed (usopen.org) and Tennis Abstract career match logs · as of 2026-09-01.
Career head-to-head: Tennis Abstract career match logs (tour-level) · as of 2026-09-01.
The briefing
Storylines
- Osaka beat Anastasia Zakharova 7-6(6) 7-6(3) in a match that finished around 12:30 a.m.; ten of her eleven aces came in the second set.
- Siniakova beat Elisabetta Cocciaretto 6-3 6-2.
- Osaka leads the head-to-head 2-1 and won the most recent meeting 6-3 6-2 at Wimbledon in 2025.
- Osaka has won this tournament twice, in 2018 and 2020, and reached the semi-finals last year; Siniakova's best US Open singles run is the third round in 2018.
- Osaka landed only 51% of her first serves on Monday and was broken four times.
Head to head
Three meetings, Osaka 2-1: she won at Doha in 2018 on a hard court and at Wimbledon in June 2025 on grass, Siniakova at Roland Garros in 2019 on clay. Their only hard-court meeting was the Doha match.
Source: Tennis Abstract career match logs (tour-level) · as of 2026-09-01.
Watch: Second-round coverage runs across ESPN, ESPN2 and ABC, with ESPN Deportes in Spanish — and every court streams in the ESPN app, which is where a match away from the two show courts will live. (ESPN press-room release and listings, as of 2026-08-27)
Court & schedule: Not yet assigned. The US Open posts each day's order of play the evening before, and this match has not reached the board yet. (Official US Open order-of-play release cadence, as of 2026-09-01)
Weather: Tonight is the last of the wet weather and the worst of it: showers and thunderstorms at 84% before the sky clears to mostly cloudy on a low near 71°F. Wednesday is the break the tournament has been waiting for — near 75°F on an 18% chance of a shower — though storms creep back after dark at 65%. Thursday is the unsettled one, warm at 81°F with showers and thunderstorms likely at 65% and 53% overnight. Friday turns: near 82°F and mostly sunny on 10%, the first clean day of the fortnight, with Saturday better still. Ashe and Armstrong close their roofs and play on; everything else waits. (National Weather Service New York forecast, as of 2026-09-01)
Venue: USTA Billie Jean King National Tennis Center, Flushing Meadows, New York — hard.
At this Stage
The Round of 64 halves the draw again: 32 women's matches across Wednesday and Thursday, every one of them between players who have already won here this week. The seeds who came through the opening round now meet opponents with form behind them rather than a ranking.
Round of 128
Round of 32