Katie Boulter secured an impressive 3-6 6-3 6-3 comeback victory against Antonia Ruzic to book a place in the Japan Open semi-finals.

Boulter got off to a worrying start in a 34-minute first set, unable to wrangle momentum back after losing the first three games of the match in succession and eventaully losing 6-3.

The British No 1 showed resilience in the second set, breaking Ruzic's serve three times in a row to force a decider. Boulter had trailed 2-0 after being broken in her opening service game, but fought back superbly to level the match.

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The world No 58 was then buoyed, winning three games in succession to open the third set and surviving a late Ruzic break to win the final set 6-3 and secure safe passage into the last four.

"[Ruzic] is a really, really good player," Boulter said of her opponent in her on-court interview on Sky Sports. "She's extremely tough to beat.

"I did extremely well to come back into it in the second set but she was swinging at everything hard. I felt like anything that I was giving her wasn't bothering her. Full credit to her.

"I tried to hang tough, and in the end I started to play a bit better. I was lucky in the second set, but in the end I felt like I did well to stay there."

Boulter will face Czech Katerina Siniakova in her semi-final match, live on Sky Sports on Saturday.

"[Siniakova] one hell of a player - she's extremely dangerous," Boulter added. "I know exactly what she's going to bring to the table.

"I think it's going to be a great match - I've got nothing to lose and I'm going to come prepared tomorrow."