Siniakova Stops Stoiana's Osaka Fairytale to Reach First Singles Semifinal in Over a Year

Katerina Siniakova has finally broken her singles semifinal drought. The Czech, better known as the world's best doubles player, swept past American qualifier Mary Stoiana 6-1, 6-2 in Friday's Osaka Open quarterfinal to reach her first WTA singles semifinal in more than a year — since the 2025 Korea Open. It was a masterclass in control. After a briefly even start, Siniakova won five straight games to take the first set, then pulled away from 2-2 in the second to close out the match in one hour and eleven minutes. The key numbers tell the story: she saved all six break points she faced, never dropped serve, won 75 percent of points against Stoiana's second serve, and broke four times. For Stoiana, the 23-year-old qualifier who began the week ranked around No. 114 after a four-match run through qualifying and into the last eight, the defeat should not overshadow an excellent week in Japan — her breakthrough at WTA 250 level after rising from outside the top 200 at the start of the season. But she met an opponent giving nothing away: Siniakova claimed 58 of the 94 points played and her return game simply suffocated the American's serve. Siniakova will now face eighth seed Katie Boulter in an all-unseeded-vs-seeded semifinal on Saturday, with a first singles final since 2025 on the line.