Riley Grabau led Wyoming (15-9, 6-5 MWC) with 17 points, and Larry Nance Jr. added 14 in the Cowboys' victory.
Nathan Sobey and Charles Hankerson both scored nine for Wyoming. The Cowboys shot 57.9 percent from the field to San Diego State's 37.9 percent, which included 5-of-21 from 3-point range.
Dwayne Polee led the Aztecs (21-2, 10-1) with 15 points. J.J. O'Brien added 11. Xavier Thames, the Aztecs' leading scorer this season, chalked up 13 but was a woeful 3-of-15 from the field, including 0-for-7 from 3-point range.
Wyoming led 32-23 at halftime and held on in the second half when San Diego State regained its footing. The Californians outscored the Cowboys 39-36 in the second period and trailed by four with 41 seconds to play but did not score on their final three shots.