Former US Open champion Samantha Stosur secured her place in a second semi-final of the year after defeating home player Misaki Doi in three sets at the WTA Japan Open.
Australian Stosur, who has had muted success since winning the 2011 US Open, overcame a second set wobble to defeat Doi 6-1 3-6 6-3 on Friday.
The third-seed's reward is a last four showdown with highly-rated American teenager Madison Keys, who advanced to her first WTA semi-final with a 6-3 6-1 win over China's Zheng Jie.
The other semi-final will see Canadian teenager Eugenie Bouchard, the No 5 seed, take on unseeded Kurumi Nara of Japan after both women came through in three sets.
Bouchard got off to a slow start before posting a 2-6 6-4 6-1 victory over Czech qualifier Barbora Zahlavova Strycova, while Nara assured the host nation a presence in the last four by scraping out a 7-6 (7/4) 2-6 6-1 win over Slovenia's Polona Hercog.