Stosur outlasts Doi to make Japan Open semis
Australia's Samantha Stosur is aiming for her fifth career WTA title
The third-seeded Stosur, aiming for her fifth career WTA title will face highly touted 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 on Saturday at the Utsubo Tennis Center will meet Canadian teenager Eugenie Bouchard, the No. 5 seed, and unseeded Kurumi Nara of Japan after both women won 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.
The 29-year-old Stosur, who had beaten Doi in Osaka in 2011 in their only previous meeting, looked like she would run away with the rematch when she zipped to a 5-0 lead before taking the first set.
But the unseeded Doi stiffened her resistance, earning a service break in the eighth game of the second set before levelling the match.
In the third set, Stosur took a 4-2 lead with a service break, only to see Doi break back. In the next game, a double fault by Doi set up a break point which Stosur converted, before holding serve to win in 1 hour, 38 minutes.
The Australian, who has had muted success since winning the 2011 US Open, had been 0-4 in quarterfinals this year until she broke through in Carlsbad in July, where she went on to win a fourth career title.
Bouchard, currently ranked 35th after starting the year at No. 145, will be looking for her first win in three semifinal appearances this year.