Pressel had eight birdies in a 7-under 64 to put pressure on the four-time Farr champion, who carried a five-stroke lead over the field through 36 holes -- and was seven shots ahead of Pressel.
Pak added a third-round 69 to her opening 63 and a 68 and is at 13-under 200. Pressel's 64 followed rounds of 68 and 70 and left her at 202 after a blustery day at Highland Meadows Golf Club.
Although Pak is just 29, the Sunday's final pairing will feature a Hall of Fame qualifier and one of the sport's rising young superstars. Pak has won 23 tournaments including five majors, while the 19-year-old Pressel become the youngest major champion in LPGA history when she took the Kraft Nabisco Championship in April.
After Pressel rolled in a 4-foot birdie putt on the closing hole, her 5-year-old cousin, Mikaela Schulz, ran onto the green and gave her a hug. Pressel picked her up and toted her to the scorer's tent while a large crowd surrounding the 18th green cheered and applauded.
For much of the day, it appeared Pak would run away and hide. Her wins at the Farr have come in 1998, 1999, 2001 and 2003.
She faltered only once on Saturday -- a three-putt bogey at the second hole -- then consistently hit fairways and greens and stayed out of trouble. At the par-4 fourth hole, she hit her approach 35 feet below the hole and then holed the birdie putt.
She had two more birdies before her wedge shot to the green at the par-4 16th was hit by a gust of wind, hit a tree limb and dropped straight down. She failed to get up and down to save her par.
Meanwhile, Pressel was climbing up the leaderboard. Even on the day through seven holes, she had birdies at holes 8, 9 and 10, then added birdies at 12, 14 and 17.
At the same time that Pak was missing a short birdie putt at 17, Pressel dropped in another birdie putt at the 18th to draw within a shot.
Pak then hit two 3 woods just short of the green on the closing par-5 hole, chipped to 4 feet and put the birdie putt in the heart of the cup.
In-Kyung Kim, who said she idolized Pak while growing up in South Korea, was the first to challenge Pak. Kim birdied the first seven holes to get to 9 under and two shots off the lead before Pak had even teed off.
But she cooled off, suffering a costly bogey at the 12th when she drove into the right rough. She finished with a 65 and was alone in third at 205.
Alena Sharp, who had a first-round 65 only to shoot a 74 on Friday, bounced back with a 67 and was fourth at 206.
Another shot back were 1988 Farr champ Laura Davies (67), Laura Diaz (68), Carri Wood (70), Linda Wessberg (66) and 2004 Farr winner Meg Mallon (70).
Jin Young Pak, no relation to Se Ri, began the day alone in second place, five shots back. She, too, said she was inspired to play golf by watching her fellow South Korean's success on the LPGA Tour. But Jin Young Pak double-bogeyed the first hole and struggled to a 74.