Katie Boulter beats Marta Kostyuk to win San Diego Open title

Katie Boulter won her first WTA 500 title by fighting back from a set down to defeat Marta Kostyuk in the San Diego Open final.

The 27-year-old Briton won 5-7 6-2 6-2 in the biggest triumph of her career so far.

After a close first set, Boulter dominated Ukrainian Kostyuk to secure a victory that lifts her to a career-high ranking of 27th in the world.

"I don't know what just happened," Boulter said after the match.

"This week has been very, very special for so many different reasons. This one is pretty amazing, I've worked very 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 that I'm very proud of."

Boulter converted seven of her 11 break points and also saved seven of the 11 that she faced.

She recovered from 5-2 down in the first set to get back to 5-5, saving five set points in the process, but Kostyuk took the opener when the Englishwoman double-faulted.

Boulter found her form and dominated from that point, breaking Kostyuk three times in the second set to force a decider. In the final set, she broke serve twice more and served out the match by hitting her first two aces of the match and a forehand winner on championship point.

Boulter was greeted by her boyfriend, Australian player Alex de Minaur, who flew from Acapulco early in the morning after retaining his title at the Mexican Open on Saturday.

"I want to say a small special thank you to my boyfriend," Boulter added.

"He finished last night at midnight and I really want to embarrass him. He got on a 4.15 taxi this morning and six o'clock flight to be here today, so I do appreciate it."

The WTA Tour includes 250, 500 and 1,000-level events - the categories denoting the number of rankings points awarded to the champion.

Boulter has risen 99 places in the rankings since winning her only other tour title at last year's Nottingham Open, a WTA 250 event.

BBC tennis correspondent Russell Fuller

Outstanding grass-court results for British players in summer have not always translated into year-round success on tour.

But Katie Boulter has built impressively on the platform of winning the Nottingham Open in June.

Consistent performances on the WTA Tour pushed her ranking into the world's top 50, and now she has been able to string together a hugely impressive run of victories in San Diego.

While Boulter did not need to beat anyone inside the top 130 to win the title in Nottingham, she saw off five top-40 players to triumph in San Diego.

She played aggressively and daringly, and as a new member of the world's top 30 is on track to be seeded for the next Grand Slam tournament, at Roland Garros in Paris, in May.