The series is even at a game apiece with Sunday's season finale scheduled for 2 p.m. (Pac-12 Networks).
The Cougars' (19-34, 11-18 Pac-12) starting pitcher Ian Hamilton went six innings, allowing three earned runs. Hamilton recorded his 70th career appearance, tying for ninth in WSU history with Adam Conley.
WSU's sole base hit was a third-inning double by J.J. Hancock.
Cal's starting pitcher, Daulton Jefferies, moved to 7-0 and is a potential first round pick in next month's MLB draft.