Trailing by a bucket with 40 seconds left in overtime, WSU scored the final four points of the game on a pair of layups by Conor Clifford and Ike Iroegbu.
Callison finished with a career-best 30 points on 12 of 16 shooting, including 6 of 9 from 3-point land. His biggest moments came after Colorado fought back to a 61-61 tie with 7:48 left. In a little more than a minute, Callison drilled three straight 3-pointers to give Wazzu a nine-point lead.
And after a Colorado trey, Callison nailed another from long distance. His body language in the second halk said it all: I can't miss.
But WSU was outscored 14-4 over the final 3:26, setting up the tense finish in overtime.
Sometimes a spark is contagious. And it came from an unlikely source for Washington State against Colorado - from beyond the arc. The Cougs entered the game shooting 32.7 percent from 3-point land. WSU was averaging 5.7 treys per game but had six in just the first half against Colorado. In the end, the Cougars hit 13 of 26 from downtown, and shot 53.8 percent from the floor.
Lost in the dizzying performance of Callison – Viont'e Daniels drilled four 3-pointers on 4 of 5 shooting while Iroegbu poured in 20 on 8 of 16 shooting, including the game winner. Iroegbu also pulled down 8 rebounds. Josh Hawkinson was 7 of 12 from the floor and finished with 18 points.
WSU got crushed in the paint 44-26 by Colorado but in addition to its 3-point sharpshooting, Washington State outscored Colorado 16-0 in fast break points.
The Cougs trailed by seven early before heating up from the floor. And as WSU gained in confidence, its ball movement looked better and better in taking a 39-35 lead into the locker room at halftime.
NEXT UP: WSU plays at No. 14 Arizona Thursday (6:30 pm, Pac-12 Network). Arizona knocked off No. 3 UCLA 96-85 on the road Saturday.