Duke freshman Virginia Elena Carta opened a six-stroke lead Sunday in the NCAA women's golf tournament and Southern California topped the 15 team qualifiers.
Carta, from Italy, shot a 6-under 66 at Eugene Country Club to reach 13-under 203. Wake Forest's Jennifer Kupcho (67), Alabama's Cheyenne Knight (71) and Miami's Dewi Weber (74) were tied for second.
The field was cut to 15 teams and nine individuals not on advancing teams for another day of stroke play Monday to determine the eight teams for match play and the individual champion.
Southern California shot a 3-over 291, with only the best four scores each day counting in the total, to reach 4-under 864. Gabriella Then led the Trojans with a 71. They are seeking their fourth NCAA title.
"I would say that each day we play the course we learn something new," Trojans coach Andrea Gaston said. "I think we might have been a little tired, and that's why we didn't play quite as sharp today. There were definitely some more difficult hole locations, but I don't think that was as much a factor, as us being a little tired."
UCLA and Duke were tied for second at 2 under. Duke had the best score of the day, an 8-under 280.
Washington (2 over) also advanced along with defending champion Stanford (4 over) and Oregon (6 over), South Carolina (8 over), Virginia (9 over), Arizona (9 over), Northwestern (12 over), Oklahoma State (12 over), Arkansas (17 over), North Carolina (17 over), Alabama (18 over) and Florida State (19 over). Florida State beat Tennessee by two strokes for the last spot.
The Pac-12 Conference had five of the top six teams and six of nine.
BYU finished last in the 24-team field at 34 over. The Cougars finished play Saturday after being allowed to start a day early because of the Mormon school's longstanding stance against participating in athletic events on Sundays.