San Diego State had one of its worst offensive performances and failed to contain the nation's leading scorer in having its unbeaten run end.
The fourth-ranked Aztecs might have an easier time at both ends of floor as they return home to face struggling Wyoming in Saturday night's Mountain West matchup.
San Diego State had its second-worst shooting effort this season (35.5 percent) and was held under 60 points for the fourth time in a 71-58 loss at No. 9 BYU on Wednesday night. The Aztecs (20-1, 5-1) also allowed the Cougars' Jimmer Fredette to score 43 points.
Despite all that, they still trailed by just four with 7:23 left before BYU pulled away on an 11-2 run.
"It was a physical game and we stayed with them for about 35 minutes, but we just couldn't hang for 40," coach Steve Fisher said.
Kawhi Leonard had 22 points and 15 rebounds for his fourth straight double-double. After scoring a combined 50 points in the previous two games, point guard D.J. Gay had a season-low two while going 0 for 5 from 3-point range and 0 for 7 overall.
Playing again at Viejas Arena might help Gay and the rest of the Aztecs, especially with the Cowboys (8-12, 1-5) visiting.
San Diego State has won 14 in a row at home and is 9-0 there this season. Wyoming, meanwhile, has dropped 17 straight on the road.
The Cowboys have also lost their past three games at Viejas by an average of 23.0 points. Leonard had 26 points to lead five players in double figures during last season's 88-57 rout there.
Wyoming heads into San Diego this time having dropped a season-high four straight. The Cowboys are also averaging 59.0 points in Mountain West play - 10.6 fewer than in their first 14 games - and giving up 71.8 per game - 8.7 more.
They led by eight points at halftime Tuesday night against UNLV before allowing 51 second-half points in a 74-65 defeat. Desmar Jackson, averaging a team-best 15.2 points, was one of three players in double figures with 17.
"This league is very unforgiving," coach Heath Schroyer said. "We have to go to San Diego on Saturday and try to do what we weren't able to tonight - guard the ball better and rebound."
Jackson had 14 points in last season's game at San Diego and Djibril Thiam scored 15 as Wyoming shot 39.2 percent and was outrebounded 43-28.
Amath M'Baye (10.5 ppg) is among three players averaging more than 9.0 points for the Cowboys along with Jackson and Thiam (10.7 ppg). San Diego State has four players averaging at least 9.5 points, led by Leonard (16.0 ppg).
The teams have split the last four games overall, and Wyoming leads the series 37-30.