Idaho held a one point, 66-65 advantage after Steven Madison hit two free throws with 30 seconds remaining in the game. Lacy drove the lane on the next possession and missed the layup, but Shelton was fouled on the rebound and converted both free throws to give the Cougars a 67-66 advantage with seven seconds on the clock.
"I got up there and realized how big those free throws would be for my team and I knew I had to make them, " Shelton said. "I am not a hero. This was a team effort. They all played hard."
Idaho's Glenn Dean drove the length of the court and found Connor Hill open in the corner for a 3-point shot with two seconds on the clock. Hill hit the back of the rim and Washington State rebounded.
"That is our home-run play and we executed it well," Idaho coach Don Verlin said. "I thought he had a good look at it, but he back-rimmed it. The game should have never come to that possession."
Washington State fell behind early. The Vandals extended a 36-33 lead into at 10-point advantage early the second half. The Cougars struggled with Idaho's zone and shot a poor 36 percent for the half.
"I am impressed with Idaho and how confident they played on defense. We had a hard time penetrating their zone in the first half," WSU coach Ken Bone said.
The Cougars found a way to penetrate the paint and expose the zone in the second half, outscoring Idaho 30-18 in the paint.
Royce Woolridge added 13 points on 5-8 shooting from the field and hit 3 of 4 from the line to help Washington State (4-4) recover from a ten-point second half deficit.
"This was a great win for our team. We played well on defense, especially well down the stretch, and hit important free throws to end the game," Bone said.
Stephen Madison had 16 points and was 9 of 10 from the free throw line for Idaho (4-5). Hill added 15 points and Dean chipped in 14. Idaho shot 80 percent from the free throw line.
The Cougars shot only 66 percent from the free throw line, but made their last four to beat Idaho for the 11th straight time.