Naomi Osaka is into the second round at the 2026 US Open, and her next test is Katerina Siniakova. The matchup renews a rivalry that reaches a fourth meeting, with Osaka carrying a 1-0 head-to-head edge and having never needed three sets to beat her before.
That is why Day 5 has become a search for Osaka now: she opened with a commanding first-round win at her happy hunting ground, but she also let big leads slip before finishing it in straight sets. The clean result mattered, but the uneven middle gave the match a different edge, one that makes this second-round preview feel less routine than a two-time US Open champion might otherwise expect.
Siniakova brings a different kind of problem. She is capable of playing high-quality tennis, and her variety can make points feel unsettled in a way Osaka does not always see early in a match. That is the appeal of this pairing. Osaka can hit through almost anyone when her timing is there, but Siniakova’s style asks her to stay sharp from the first game rather than drift through a comfortable rhythm.
The wider Day 5 card also underlines how much talent is moving through New York right now. Naomi Osaka is one of the headline names, with Elena Rybakina also on the slate, while Amanda Anisimova advanced after losing just four games, Elise Mertens moved on without being broken, and Anastasia Potapova beat Darja Semenistsja 6-2 6-2 with 10 aces. Maria Timofeeva, meanwhile, qualified for the main draw for the first time and is experiencing her first match in New York, another sign of how quickly the draw is shifting around the established names.
For Osaka, the important question is not whether she can handle Siniakova at her best. It is whether she can close sooner and cleaner than she did in the first round. If she does, the fourth meeting may look like the previous three. If she does not, Siniakova has the kind of variety that can turn a familiar matchup into something far less predictable.
