Melvin Ejim and DeAndre Kane each scored 21 points, leading the Cyclones to a 90-88 come-from-behind victory against the Cougars on Wednesday night.
Kane, who was ejected for a flagrant-2 foul with 3:28 remaining, had a team-high 11 rebounds for the Cyclones. Georges Niang added 19 points, eight assists and five rebounds for Iowa State (4-0).
Iowa State took the lead for good with six minutes remaining on a 3-pointer by Matt Thomas, who finished with 12 points. The Cyclones stayed in front with three clutch baskets down the stretch by Niang.
"We really tried to get the ball to Georges and isolate him and let him go make plays," Iowa State coach Fred Hoiberg said. "I thought we did a good job of getting him the ball where he needed it, and our spacing was good so he had the room he needed to make plays. That's what you want out of your go-to guy down the stretch."
The Cougars, who led for more than 26 consecutive minutes, got 20 points from Tyler Haws and 19 points and seven assists from Matt Carlino. Freshman Eric Mika scored 17 points and pulled down nine boards.
The Cougars (4-1) had a chance to take the lead in the final seconds but Daniel Edozie blocked a foul-line jumper by Haws with 4 seconds remaining and then hit 1 of 2 free throws on the other end.
Edozie came over to help when Haws twisted in the paint, figuring BYU's leading scorer was gearing up to attempt a fade away jumper.
"I went up as he went up and came away with a clean block and came away with the ball and came away with some free throws. Fortunately I was able to bank one of them in," said Edozie, who was inserted in the game late for his defense.
An off-balance jumper by BYU's Kyle Collinsworth that would have tied the game at the buzzer bounced long off the rim.
"We had quite a few chances there at the end to make a few plays and win the game, but it just seemed like they were a little bit better in their execution late in the game," BYU coach Dave Rose said.
After fighting back from a 12-point first-half deficit to take a five-point lead, the Cyclones let BYU back in the game when Kane, with 3:28 remaining, jammed his fingers into Mika's face before the freshman center could go up for a shot in the paint. The officials assessed a flagrant foul that resulted in Kane's ejection.
Following the game the officials issued a statement saying they deemed Kane's foul to be "severe or extreme" while the ball was still live.
With Mika out Haws hit two free throws, and then made two more free throws after being fouled on the ensuing inbounds play to cut the lead to 82-81.
But back-to-back jumpers by Niang pushed Iowa State back in front by five. Niang hit another baseline jumper with 1:23 remaining after Haws had made two more free throws.
"I don't think the game got away from us," Haws said. "We knew we had a chance to win the game and we had our chances down the stretch. We just didn't make the plays we needed to."
Haws made only 6 of 19 shots.
"What you have to do is make him take tough shots, even though he's going to make tough shots. I thought we did as good as job as we possibly could against him," Hoiberg said.
The Cougars, who haven't defeated a non-conference ranked team at home since 1986, used a 21-8 run midway through the first half to take a 36-24 lead. The run was led by three consecutive baskets by Carlino and two long feeds from the junior point guard that resulted in a fast-break layup by Anson Winder and an alley-oop dunk by Mika.
Iowa State, with two late 3-pointers by Ejim, cut BYU's margin to 47-42 at the break.
The Cyclones got within a basket five times early in the second half only to be answered by BYU each time. Iowa State finally broke through for good on Thomas' 3 from the right wing.
"With BYU, we knew this was going to be a game of runs. They can really heat up in a hurry and they are as fast of a team as any in the nation, and they lived up to that tonight," Hoiberg said. "They scored in bunches. But I thought the two keys were us getting back in transition and finally finding a way to battle them on the boards. Once we could get it off the board we were able to get out and run."
Iowa State shot 58 percent in the second half and 51 percent for the game. The Cylones also outrebounded the taller Cougars by 12 boards in the second half and finished with a 46-44 rebound advantage.
The Cougars stayed in front most of the game by scoring 20 points off 13 Iowa State turnovers. BYU took 84 shots to 70 for the Cyclones.