Fredette scored 20 of his points in the second half as BYU (21-6, 9-4 Mountain West) overcame a 14-point deficit early in the half. With the Cougars still trailing 55-49 with seven minutes left, Jackson Emery hit a 3-pointer to start the 15-0 run. Fredette scored nine straight points before Emery capped the run with another 3-pointer to give BYU a 64-55 lead with 48 seconds left.
After shooting 25.8 percent from the floor in the first half, the Cougars were more patient as they hit 59 percent of their shots in the second half.
San Diego State (18-8, 8-5) had its 10-game home win streak snapped as BYU's second-half zone defense slowed down its offense after the Aztecs led 33-20 at halftime.
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Lorrenzo Wade led San Diego State with 19 points and Kyle Spain and Tim Shelton added 13 each.