American qualifier Amanda Anisimova is in her first WTA final at age 17 after upsetting top-seeded Zhang Shuai of China 7-6 (4) 7-5 at the Japan Women's Open.
Trailing 5-4 in the second set on Saturday, Anisimova hit two fierce winners down the line and went on to win with her first match point as Zhang's backhand went long.
Anisimova, who turned 17 just two weeks ago, is the youngest player to reach a final since 16-year-old Donna Vekic at Tashkent in 2012 and Birmingham in 2013.
Anisimova will face Taiwan's Hsieh Su-Wei in Sunday's final.
Hsieh overpowered China's Qiang Wang 6-4 6-4 in Saturday's other semi-final.
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Second-seeded Hsieh earlier beat Australia's Ajla Tomljanovic 4-6 6-2 6-0 in a quarter-final held over from Friday because of rain.
