Katie Boulter recovered from a set and a break down to beat Croatia’s Antonia Ruzic 3-6 6-3 6-3 in the Japan Open quarter-finals in Osaka on Friday. The Katie Boulter Japan Open win also hands her back the British women’s number one ranking from Sonay Kartal.
Boulter had lost that status only on Monday. Five days and three wins later it’s hers again, and she’s guaranteed a return to the world’s top 50 for the first time since last year, however her semi-final goes.
How Boulter turned the quarter-final around
Eighth seed Boulter trailed world number 91 Ruzic by a set and a break but recovered to win 3-6 6-3 6-3 in two hours, according to BBC Sport. Ruzic, 23, controlled the early exchanges. She sprinted out into a 3-0 lead before Boulter managed to get on the board, and when the Briton got a break back, the Croatian broke straight back and served out the set.
The second set was scrappy, and that suited Boulter. She trailed 2-0 after dropping her opening service game. She saved two break points in the third game to avoid going a double-break down before coming up with a crucial hold in the seventh after the pair had exchanged three successive breaks.
That hold kicked off a run of eight straight games that took her into a 4-0 lead in the decider. There was one late wobble. She was broken while serving for the match at 5-2, but she immediately broke Ruzic to love to close out the victory, and finished it with a forehand winner on match point.
The key numbers from the Ruzic match
On serve, this was not a clean performance. Boulter struggled on serve in the opening two sets, winning just 60% points behind her first serve, hitting four double faults, and facing seven break points, BBC Sport reported. What changed was her court position. She started stepping inside the baseline to put pressure on the 23-year-old Croat, and Ruzic’s error count climbed.
The quarter-final was the first real test of her week. She had beaten Himeno Sakatsume 6-3 6-1 and Viktorija Golubic 6-2 6-1 to get there, dropping just seven games across the two matches. The week started awkwardly, though. During her first-round match she showed the umpire the weather app on her phone, on court, ahead of play being suspended, Sky Sports reported.
- First round: beat Himeno Sakatsume 6-3 6-1
- Second round: beat Viktorija Golubic 6-2 6-1
- Quarter-final: beat Antonia Ruzic 3-6 6-3 6-3
- Semi-final: Katerina Siniakova, Saturday 24 October
Katie Boulter Japan Open run settles the British number one race, for now
The domestic ranking flipped on Monday after Kartal reached the final of the Wuhan Open. That run left Boulter 55 points behind her compatriot, and she knew going into Osaka that reaching the last four would be enough to close the gap. Boulter’s progress in the tournament overturned her 55-point deficit in the rankings and dethroned Kartal back to the No 2 spot, Sky Sports said.
Boulter came into the event at world No 58. According to Tennis Uptodate, the former World No.23 is set to rise to 48th in the world, with Kartal moving outside the top 50 thanks to results around her. The same outlet reported that she will be the World No.44 if she makes the final, with a title boosting her another spot to 43rd. The new rankings come out on Monday.
The swap says more about how tight things are at the top of the British women’s game than about any big gap in form. Kartal’s Wuhan run was a significant step forward in her own right. Boulter’s response was to answer it inside a week.
What Boulter said after the win
Boulter gave Ruzic plenty of credit in her on-court interview. “[Ruzic] is a really good player,” Boulter said of her opponent in her on-court interview on Sky Sports. She was honest about how the match swung, too. “I did extremely well to come back into it in the second set but she was swinging at everything hard.”
She also admitted the breaks went her way at a key moment. “I was a bit lucky in the middle of the second [set] but I feel I did really well to stay there,” she told BBC Sport.
Looking ahead to Siniakova, she didn’t play down the threat. “She’s one hell of a player, extremely dangerous. It’s going to be who gets the first strike in.” She added, according to Tennis365, that “I’ve got nothing to lose and I’m going to come prepared tomorrow.”
Background: Boulter’s 2026 season so far
This is Boulter’s third WTA semi-final of 2026 and her first since Queen’s in June. Her one title this year came in Ostrava in February. That win marked a return to form after a difficult 2025 that had seen her slide down the rankings.
She has spoken this week about liking the conditions in Osaka, saying the slightly quicker courts suit her game better than the slower surfaces common elsewhere on the tour. At 30, and at 6ft, she wins most points with first-strike tennis, and the Ruzic match showed both sides of that. When the serve misfired she was exposed. When she moved forward and took time away from her opponent, the match changed.
Next up at the Japan Open: Katerina Siniakova
Boulter’s semi-final opponent is better known for her doubles. Siniakova is the world doubles No 1 and ranked 86th in singles. She has had a strong week in Osaka. Siniakova has played some excellent tennis so far this week, upsetting the second seed Peyton Stearns (albeit benefitting from the American’s retirement) before dismissing Magda Linette and young gun Mary Stoiana to reach the last four. Her quarter-final against the qualifier Stoiana finished 6-1 6-2.
The pair have met once before. Boulter won their previous encounter 4-6, 6-2, 6-1 on the clay in Madrid in 2025, Tennis365 noted. Hard courts in Osaka are a different test, and Siniakova’s all-court game and doubles instincts at the net could make for a quicker, more tactical match than the Ruzic slugfest.
The semi-final was scheduled for Saturday afternoon local time on Court 1 in Osaka, with Sky Sports showing it live in the UK. The other semi-final in Osaka, which is a WTA 250 tournament, is the all-American clash between top seed Ann Li and Ashlyn Krueger.
Frequently Asked Questions
Who did Katie Boulter beat at the Japan Open quarter-final?
Boulter beat Croatia’s Antonia Ruzic, the world No 91, 3-6 6-3 6-3 in two hours in Osaka. She came back from a set and a break down.
Is Katie Boulter British number one again?
Yes. Reaching the Japan Open semi-finals overturned a 55-point deficit to Sonay Kartal, and Boulter will be British No 1 when the WTA rankings update on Monday.
Who does Katie Boulter play in the Japan Open semi-final?
She plays Czech Katerina Siniakova, the world doubles No 1 and singles No 86. Boulter won their only previous meeting, 4-6 6-2 6-1 in Madrid in 2025.
The Katie Boulter Japan Open run now hinges on whether she can solve Siniakova on a court she says suits her. Monday’s rankings will confirm her climb, but a place in the final would lift her to around 44th and give her a cushion over Kartal heading into the last weeks of the season.
Sources:BBC Sport (via Yahoo Sports), Sky Sports, Tennis365, Tennis Uptodate
