Freshman Everett Winchester scored 14 points and grabbed six rebounds, while junior Mark Hughes had 13 and freshman Jaylon Hall contributed 10.
The Raiders hit a season-high 11 3-pointers on 21 attempts and were 30 of 60 overall.
They held the Phoenix to 23 of 64 shooting, with half of those attempts coming from beyond the arc (8 of 32).
WSU returns to action at 8 p.m. Saturday night at Milwaukee.
Northern Kentucky thumped the Panthers 91-64 Thursday night to stay one game behind the Raiders.