After forcing a turnover with 4:03 to play, Marcus Paige attempted to close the Cyclones' coffin door with a 3-pointer from the left wing 10 seconds later. The sophomore guard misfired, however, and Naz Long collected the rebound and drained a trey on the other end.
A charge call on James Michael McAdoo gave UNC an empty possession with 3:14 to play, and following the final media timeout, Monte Morris buried a 3-ball to pull Iowa State within two points at 76-74. Kennedy Meeks forced a putback on the Tar Heels' next trip down – rushing a shot on his way down – and Melvin Ejim tied the game on a layup with 2:03 to play.
UNC and Iowa State traded baskets over the next four possessions before a critical error by Paige with 31 seconds to play allowed the Cyclones to retake the lead for the first time since the 10:17 to play. Paige drove into the lane, got caught in the air and tried to find McAdoo, who had already cut to the basket. Ejim stole the pass and DeAndre Kane gave his team the lead at 83-81.
Iowa State scored three times within six seconds following a UNC possession in the final 2:03.
"We needed to do a better job of getting back in defensive transition, there is no question," UNC head coach Roy Williams told reporters during his postgame press conference.
After McAdoo tied the score with a pair of free throws with 15 seconds remaining, Kane took Tokoto off the dribble, penetrated into the lane and made the game-winning layup with 1.6 seconds left.
"The last second shot was just an unbelievable play," senior guard Leslie McDonald said.
The Cyclones, who had shot 37.9 percent over the first 36 minutes and 15 seconds, connected on seven of their last eight field goal attempts, including all three 3-pointers.
The Tar Heels, on the other hand, missed four of six shots and committed a pair of turnovers in their final six possessions.
Williams described the final 3:45 as a combination of Iowa State making plays and missed opportunities by his squad.
"You've got to congratulate them on making plays," Williams said. "Yeah, it would have been nice to get some points on three straight possessions when we didn't get points. Because after Marcus missed the jump shot and James Michael got the offensive foul called, Kenny got the offensive rebound and missed the lay up. So it was a little bit of both. We didn't capitalize when we had the ball."
During a 12-game winning streak that vaulted UNC from 15th in the ACC to the No. 4 seed in the conference tournament, the boys in blue found ways to grind out victories down the stretch.
UNC fell a play short as its season came to a close at the AT&T Center on Sunday.