LAS VEGAS (AP) _ Terrell Lyday scored 18 of his 25 points in the second half Thursday as Brigham Young rallied from an 11-point second-half deficit to beat Air Force 69-54 in a first-round game of the Mountain West Conference tournament.

Lyday made four of his five 3-point shots after halftime as the Cougars (22-8) advanced into Friday's semifinals.

Air Force (8-21) led 31-25 at halftime, and scored the first five points of the second half before BYU began its comeback. The Cougars started by scoring eight straight points including 3-pointers by Trent Whiting and Lyday to draw within three points.

A dunk by Lyday with 12:45 to play put BYU on top 40-39, and the Cougars, who made 9-of-15 3-point shots, led the rest of the way.

Whiting finished with 17 points, five rebounds and five assists and Mekeli Wesley added 13 points for the Cougars.

Lamoni Yazzie led Air Force with 12 points, and Tom Bellaris and Vernard Jenkins added 11 points each for the Falcons.