Leona Maguire slumped to a second-round 76 to miss the LA Open cut on the LPGA Tour as Stephanie Meadow also exited.
Cavan woman Maguire, 26, produced the best performance of her LPGA career when sharing second place at last week's Lotte Championship in Hawaii.
She was only five off the pace after the opening round in Los Angeles but failed to record a birdie on Thursday.
Her three-over-par total left her one outside the cut with Meadow's 76 putting her on seven over.
After an opening 73, the 29-year-old Northern Irishwoman needed to improve to have any hope of surviving into the final 36 holes but she produced an erratic round which included six bogeys and a double bogey.
Maguire, meanwhile, had three bogeys and a double bogey as her run of impressive form came to something of an abrupt and surprising halt.
The Irishwoman double bogeyed the sixth to drop back to level par and after parring her next eight holes, then suffered three straight bogeys from the 15th.
Following her share of second place last week, Maguire moved up 25 places to 93rd in the world rankings, the first time she had entered the top 100 since turning professional in 2018.
Maguire's high finish last week also shot her up to 10th in the LPGA's season standings with world number 111 Meadow in 62nd spot going into the Los Angeles event.
Overnight leader Jessica Korda extended her lead after adding a 65 to her opening 64.
The US player's 13-under-par total - a 36-hole record for the event - leaves her three ahead of world number one Jin Young Ko and another South Korean Sei Young Kim.
Canada's Brooke Henderson and American Angela Stanford are sharing fourth place on eight under.