Katie Boulter beaten by Barbora Siniakova in Japan Open semi-final

Katie Boulter lost 6-1 6-4 to Barbora Siniakova in the Japan Open semi-finals in Osaka on 24 October 2026, her first match since reclaiming the British number one ranking from Sonny Kartal. The defeat ended her bid for a place in the final and a chance at a fifth WTA singles title.

Kartal had moved above Boulter in the world rankings by reaching the final of last week's Wuhan Open, but Boulter's run to the last four in Osaka — which included a quarter-final victory over Antonia Ruzic — will be enough for her to return above Kartal when the rankings are next updated. Boulter is the tournament's eighth seed and the 30-year-old's last WTA title came at the Ostrava Open in February.

Siniakova, the doubles world number one and also 30, defeated Boulter 6-1 6-4 in a match that lasted 85 minutes. Boulter was swept aside in the opening set before rallying to go a break up at the start of the second. Siniakova secured two hard-fought breaks to close out the victory.

Ashlyn Krueger beat compatriot and top seed Ann Li 6-4 6-7 (4-7) 6-3 in the other semi-final. Krueger is the 22-year-old American who won this event in 2023. Ann Li was the tournament's top seed.

Siniakova will meet Krueger in Sunday's final in Osaka, with the doubles world number one still pursuing her first singles title in four years.