Provo • Despite leading for much of the game, BYU could not knock off No. 21 Iowa State on Wednesday night at the Marriott Center.The Cyclones used a big second half and handed the Cougars their first loss of the season, 90-88.BYU's Kyle Collinsworth had a chance to send the game into overtime, but his jumper as the buzzer did not draw iron.Iowa State improved to 4-0 with the win, after trailing by as many as 12 points in the first half.Tyler Haws led BYU with 20 points and Matt Carlino added 19. Melvin Ejim and DeAndre Kane had 21 for ISU and Georges Niang added 19, including three short jumpers in the final four minutes.BYU's Anson Winder made one of two free throws with 24 seconds left to trim the deficit to one, but Haws' jumper in the lane was blocked by ISU's Daniel Edozie with less than 10 seconds remaining.Collinsworth got off his shot after Edozie made a free throw with 3.2 seconds left.The Cylones took a 78-77 lead on a 3-pointer by Matt Thomas with 5:54 remaining in the game, their first lead since midway through the first half, and held on to get the upset.The Cougars looked like they were going to run the Cyclones out of the gym in the first half, and when Eric Mika slammed home a fast-break lob from Matt Carlino to give BYU a 36-24 lead, the crowd noise was deafening.Iowa State got back into it with 3-point shooting, as Naz Long buried a long one and Ejim got hot with a pair of treys. A pair of free throws pushed an ISU run to 10-0 before the Cougars scored the last four points of the first half to take a 47-42 lead into the locker room.The half featured only seven free throws and was filled with fast-paced action, including 43 possessions. The Cougars used their height advantage effectively, out-rebounding the Cyclones 27-19 in the first 20 minutes.