Nirapathpongporn will face In-Bee Park in the semifinal round Saturday. Park advanced thanks to a 3 and 1 victory over Ashley Knoll in Friday's quarterfinal action.
Saturday's other semifinal will feature Jane Park, who moved on with a 2-up win over defending champion Becky Lucidi, versus Paula Creamer, who trounced Erica Blasberg 6 and 5 Friday.
Nirapathpongporn built a 2-up lead over Song on the front nine but Song roared back to square the match with a win on the ninth hole. Song actually went ahead with a birdie at 10 but Nirapathpongporn drew even when Song bogeyed No. 13.
Nirapathpongporn birdied 14 and 16 to go 2-up with two to play. Nirapathpongporn bogeyed the 17th when her drive kicked left and at 18 both players bogeyed the hole to give Nirapathpongporn the 1-up victory.
'It's good to play someone that brings it on to you, because then you learn how to hit shots under pressure and that's what you got to take to the final match,' said Nirapathpongporn, an All-American at Duke University. 'Tomorrow is going to be a good match, too.'
In-Bee Park, who won last year's U.S. Girls' Junior Championship, was 3-up through 11 holes but lost the 12th when Knoll birdied the par-5 hole. In- Bee Park held a 2-up lead through the rest of the match until she birdied 17 to post a 3 and 1 victory.
Jane Park took a 1-up lead at the second hole and Lucidi was unable to square the match until the 13th hole when Jane Park bogeyed and Lucidi birdied. Jane Park immediately reclaimed the 1-up lead at 14 but Lucidi squared the match at No. 16.
Lucidi bogeyed 17 to fall 1-down and Lucidi made a mess of 18 to give Jane Park the spot in the semifinals.
'When I got to all-square I got a little shaky, but I just sucked it up and made a par and she made bogey unfortunately,' said Jane Park, referring to the 17th. 'So it was a tough match.'
Creamer amassed a 5-up lead at the turn and the match ended shortly after that at 13 when Creamer and Blasberg halved the hole.
'I played good golf today,' said Creamer. 'It just really wasn't Erica's day out there. My putter was hot. In match play, that's not what you really want to get up against. She is a great player and I had a lot of fun out there.'