Tangtiphaiboontana, 17, of Long Beach, Calif., beat Allison Martin of Bakersfield, Calif., 2 and 1, in her semifinal match at the Echo Lake Country Club.
Tangtiphaiboontana will play qualifying medalist In-Bee Park, 14, of Eustis, Fla., on Saturday. Park beat Hannah Jun of San Diego in 20 holes in the other semifinal.
``I'm actually pretty excited,'' Tangtiphaiboontana said. ``I was pretty happy just making it to the quarterfinals. When I won this match, it was like: `Wow.' It's all pretty overwhelming.''
In November, Tangtiphaiboontana's parents died in an automobile accident on the way home from a state tournament in California.
Tangtiphaiboontana and her best friend, Dianne Sirisut, were riding in the vehicle. Tangtiphaiboontana sustained only minor cuts and scratches and returned to play golf only a few weeks later.
``There have been certain periods when I'm not playing well, or I'm stressed out, I say, 'Why am I still playing?''' she said. ``But I don't mean that seriously.''
In her mother's memory, Tangtiphaiboontana carries a red blouse that her mother used to wear during the final rounds of tournaments.
Her brother 19-year-old brother Tommy, who attends Yale, has taken time from pursuing college internships this summer to be with her. Tangtiphaiboontana, still living on the West Coast with a family friend, said she talks to her brother every night.
``He has taken my mom's place,'' she said. ``It's a little easier. It's nice to have someone here. I'm just kind of trying to repay him; so far I think it's working.''
After beating Amie Cochran, 16, of Torrance, Calif., in 20 holes in the quarterfinal, Tangtiphaiboontana won the first two holes in the semifinal match. Martin squared the match by the seventh hole, but it would be closest she would get.
Tangtiphaiboontana pushed her lead back to 2-up on the 16th hole, when Martin missed a 7-foot putt for par. Tangtiphaiboontana ended the match on the 17th.
Tangtiphaiboontana hasn't wondered about winning.
``I've managed to shut it all out,'' she said.
Park went to extra holes to win both matches. She needed 22 holes to beat Jean Reynolds, 17, of Newnan, Ga. in the morning, and then spoiled Jun's 17th birthday in the afternoon.