British No1 Katie Boulter secured the biggest title of her career to date with victory over No6 seed Marta Kostyuk at the San Diego Open.

The 27-year-old fought back from a first-set deficit to beat her Ukrainian opponent 5-7 6-2 6-2 on Sunday night.

And in the process it catapulted her up the world rankings to a career-high 27th.

Boulter had picked up her first WTA Tour title in Nottingham last summer but this was a step up at a WTA 500 event.

“I don’t know what just happened,” she said afterwards. “This week has been very, very special for so many different reasons. This one is pretty amazing. I’ve worked hard for it, I played some incredible tennis all week.

“Today was a complete battle with myself as well because I was a little bit nervous. But I managed to get over the line and I’m very proud.

“A lot of it was about me staying as tough as I possibly could mentally and I managed to keep my cool and actually kind of went within myself and calmed myself down a lot. I think that really helped me, and then I started to relax and play through shots a little bit more.”

Boulter, watched by her boyfriend Alex de Minaur, who had taken a 6am flight in the wake of his own title success at the Mexican Open to be in attendance, did well to stay in the opening set, overturning a deficit to level the scores at five games apiece only for Kostyuk, also a tour title winner for the first time in 2023, to break again and take the opening set.

Her British rival raised the stakes in the next set, serving well and playing aggressively from the baseline to level the match and then dominate the decider for victory in just over two hours.

She was quick to pay tribute to De Minaur for being in her player’s box for the final.

“I want to say a small special thank you to my boyfriend,” she said. “He finished last night at midnight and I really want to embarrass him.

“He got in a 4.15 taxi this morning and six o’clock flight to be here today, so I do appreciate it.”