USC rallied from a 3-0 deficit to beat Stanford 6-3 in 10 innings at Sunken Diamond on Sunday.
The Cardinal's Chris Viall allowed just one run and one hit in six innings. His only blemish was a home run by Vahn Bozoian in the sixth.
Alex Dunlap had a two-run double, and Danny Diekroeger had a sacrifice fly for Stanford (8-10, 1-2 Pac-12), which dropped two of three to the Trojans.
USC tied it with two in the eighth, both on sacrifice flies, before scoring three times in the 10th.
Nick Halamandaris was 3 for 4 with a homer, but Cal (11-11) lost at sixth-ranked Cal Poly 8-4. Derek Campbell also homered for Cal.
Anthony Gonsolin pitched seven shutout innings, and Saint Mary (11-12, 3-0 WCC) beat host Portland 2-0 to complete a three-game sweep. The Gaels scored in the fifth on RBI singles by Ricky Boas and Anthony Villa.
Santa Clara (9-14, 0-3 WCC) lost 10-0 to Pepperdine at Stephen Schott Stadium. The Waves put up 10 runs in the last four innings to win for the third time in three days.
San Jose State (7-18, 4-8 Mountain West) lost 9-4 at New Mexico. SJSU was shut out until the ninth.
No. 24 Stanford (23-10, 1-4 Pac-12) was routed 9-0 by No. 11 Arizona State in Tempe, a day after losing 16-15 in nine innings.
San Jose State (17-13) beat UC Santa Barbara 6-3, then fell to Long Beach State 9-6 in San Diego.