Layshia Clarendon netted 22 points in No. 6 California's 72-64 win over Southern California.
Brittany Boyd added 16 points and six rebounds for the Golden Bears (23-2, 13-1 Pac-12), who remained tied for first-place in conference with Stanford, which defeated UCLA on Sunday.
Cassie Harberts had 20 points to lead USC (8-17, 5-9).
USC trailed by as many as 13 points in the second half, but battled back and Harberts' jumper with 1:54 left pulled the Trojans within 63-59, but they got no closer as Clarendon's three-point play at the other end essentially sealed the outcome.
Cal took a 38-29 advantage into the break.