British number one Katie Boulter stormed through to her first WTA 500 semi-final with a straight-set victory over Croatia's Donna Vekic at the San Diego Open.

Boulter overcame strong winds in California to wrap up a 6-4 6-3 win over the seventh seed.

The 27-year-old will play Daria Saville of Australia or American third seed Emma Navarro in the last four.

"It was an absolute battle in very tricky conditions," said Boulter.

"It was not easy to get any rhythm because we are both big hitters. I found it tough to get into the match and just tried to stay as strong as I could in the head.

"Somehow I found a way over the line in the first and played some really good stuff in the second."

Boulter, ranked 49 in the world, will move up to the brink of the top 40 and a career-high ranking after this latest win.

World number 28 Vekic started strongly and made the first break of the match to move into a 3-1 lead.

But Boulter, who beat second seed Beatriz Haddad Maia in the last round, surged back into the match, winning nine of the next 10 games to take the first set and race into a 4-0 lead in the second.

She then converted her first match point with a powerful forehand after the longest rally of the match to seal the win.