PROVO, Utah -- BYU coach Dave Rose knew rebounding would be important for his Cougars (No. 11 ESPN/USA Today, No. 13 AP) against San Diego State.
Emery had seven rebounds and Fredette grabbed six to help the Cougars outwork the conference's best rebounding team, 38-37.
"Jackson and Jimmer were terrific," Rose said. "San Diego State relies so much on offensive rebounds to score that they send three and sometimes four guys to the boards. If you secure the ball you'll have some opportunities to beat them back down the floor."
BYU finished with a 20-4 edge in fastbreak points.
"Every time we missed a shot they attacked and that resulted in too many easy baskets," Aztec coach Steve Fisher said. "They are not 26-3 for no reason. They are really good."
The Cougars' 21st straight home victory set up the biggest regular season showdown in Mountain West history based on rankings as they host No. 10 New Mexico on Saturday. The winner will take the conference lead heading into the season's final week.
"It's a huge win," Rose said, "especially knowing you have a huge game Saturday. You lose here and you get rattled a little bit going in to a play team on a 12-game winning streak."
D.J. Gay scored 15 points to lead San Diego State (20-8, 9-5).
Fredette and Emery scored three points each in the Cougars' 14-2 run midway through the second half to break open a tight game.
Fredette was 4 for 8 on 3-pointers after being named a Naismith Trophy nominee earlier in the day.
"Jimmer is the best in the league," Fisher said. "He is as good a guard as I have seen in this league."
Fredette and Emery grabbed 11 of their 13 rebounds after Aztec misses.
"Our first and second keys was to have the guards rebound, and we did," Fredette said. "We did a good job keeping them off the glass."
The Cougars made 7-of-15 3-pointers.
The conference's leading rebounder, Kawhi Leonard, played just 24 minutes for the Aztecs because of illness. Leonard scored three points and grabbed five rebounds, five below his average.
The game went back and forth in the first half. After 11 lead changes, Malcolm Thomas made two free throws to tie the score at 25.
BYU then went on an 11-0 run, led by seven points by Emery, who sensed the Aztecs were tired playing with a short bench at a high altitude.
"They kept subbing in and out," Emery said. "That mentally turns on a trigger that you should keep pushing the ball."
San Diego State tied the score at 44, but Jonathan Tavernari scored in the lane and Emery hit a 3-pointer to start the 14-2 run.
Maryland point guard Melo Trimble has withdrawn from the NBA draft and will return to College Park for his junior season, sources told ESPN.
Louisville's Chinanu Onuaku, who recently underwent a medical procedure to correct a heart rhythm issue detected during the combine, will keep his name in the NBA draft pool.
Andrew White III will return to the Nebraska men's basketball team next season after removing his name from the NBA draft.