Auckland - Croatian teenager Ana Konjuh outlasted Julia Goerges in a two-hour battle on Friday to set up a final against diminutive American Lauren Davis in the WTA Auckland Classic.
Konjuh, 19, a former Australian and US Open junior champion, surprised herself with the way she rallied to beat 28-year-old Goerges, last year's runner-up, 6-3, 4-6, 6-3.
"When I came here I wasn't playing that well, and my serve wasn't that good tonight," Konjuh said, after downing Goerges despite serving eight double faults and having only a 49 percent first-serve success rate.
In the other semi-final, the 1.57 metre Davis was leading Jelena Ostapenko 4-6, 6-4, 4-1 when the Latvian, who was suffering from a viral illness, pulled out.
The seventh seed had started strongly, breaking Davis twice to go 5-1 up before taking the set 6-4.
But as she began to wilt she dropped the second set 4-6 and looked drained as play progressed in the third.
"She was playing good, but I had good chances in the second set to win the match, but then I didn't and unfortunately I couldn't finish the tournament," Ostapenko said.
"During the match my throat was very painful. My concentration wasn't good. I wanted to play, but just couldn't, because I'm sick."
Davis has advanced a step further than her previous best in Auckland, when she lost to fellow American Venus Williams in the 2015 semi-finals.
For Konjuh it is only the second time she has made a WTA final after winning in Nottingham last year as an 18-year-old.
Despite an erratic serve, the tenacious Konjuh had too much variation in her ground strokes for Goerges who was unable to repeat the consistency with her serve and forehand which she showed when beating Caroline Wozniacki in the quarter-finals.
Konjuh and Davis have met once before, in Auckland in 2014, with Davis prevailing in three sets.
Results from the fifth day of the WTA Auckland Classic tennis tournament on Friday (X denotes seed):
Lauren Davis (USA) bt Jelena Ostapenko (LAT x7) 4-6, 6-4, 4-1 (retired)
Ana Konjuh (CRO x8) bt Julia Goerges (GER) 6-3, 4-6, 6-3