The 17-year-old Pressel lost to Colombian Juliana Murcia Ortiz, who rallied from two holes down before chipping in for birdie to win the match in 19 holes.
'I feel great,' said the 17-year-old Murcia Ortiz, who went on to defeat Hsiao-Ching Lu 2 & 1 in the quarterfinal round at BanBury Golf Club. 'It was a really tough match.'
But an exciting one to follow.
After Murcia Ortiz pulled within one stroke by sinking a 15-foot birdie putt on No. 17, Pressel allowed her opponent to tie the match when she hit her second shot into the hazard left of the 18th green.
The two golfers headed to the par-4 first hole, where Muria Ortiz came up 40 feet short of the green. Pressel was in better shape -- on the green in two and looking at a 12-foot birdie putt.
But Murcia Ortiz's chip trickled in, and Pressel's putt broke left past the hole.
Pressel experienced a similar moment at the Women's Open when Birdie Kim chipped in from a greenside bunker at the 18th hole. She was tied for the lead in the 18th fairway until Kim's hole-out, and ended up finishing two strokes back in a tie for second place.
'This hurts more,' said Pressel. 'Obviously, she played well enough to win. But I kind of gave it away a little bit on 18.'
Murcia Ortiz advanced to Friday's semifinals, where she will face Korean In-Kyung Kim, who beat 2004 U.S. Women's Amateur Public Links champion Ya-Ni Tseng of Chinese Taipei in 20 holes in round three before ousting Stephanie Connelly 3 and 2 in the quarters.
Friday's other semifinal match will pit Joanne Lee of San Carlos, Calif., against 2002 Girls' Junior Champion In-Bee Park of Las Vegas.
Lee beat Cheyenne Woods, 4 and 3, in the third round before dispatching Amber Lundskog in the quarterfinals. Park ousted Kimberly Kim, 3 and 1, and knocked off Sydnee Michaels 2-up in the quarters.
The 18-hole championship final is scheduled for Saturday.
The U.S. Girls' Junior was established in 1949 and is open to any female golfer who has not reached her 18th birthday by the close of the competition and has a USGA Handicap Index that does not exceed 18.4. The Girls' Junior is one of 13 national championships conducted annually by the USGA, 10 of which are strictly for amateurs.