The Huskies held on for an 87-82 upset but not before giving Plum a scare. Stanford cut a 12-point deficit with 39 seconds left down to three with 8 seconds on the clock.
"That's the most nervous I've ever been in my life," Plum said. "I was sitting there grabbing people's knees and elbows, and biting towels and stuff. But we had a silent confidence that we earned that game and we're not going to give it away in the last minute."
Aminah Williams sealed the win for the Huskies, making a pair of free throws with 4 seconds remaining, and as the final buzzer rang the Washington players danced in celebration at half court.
Plum scored 23 points, one of five players in double figures for the Huskies, which led almost the entire game. It was the highest-ranked opponent the Huskies have beaten since winning against No. 2 Stanford in 1990.
The loss snapped a 62-game road conference winning streak for Stanford (22-2, 11-1 Pac-12), as well as a 14-game run against Washington (13-10, 6-6). The Cardinal's last loss in road or neutral conference games was Jan. 18, 2009, against California in Berkeley. Stanford's only other loss this year came at No. 1 Connecticut.
"That was crazy," said Washington forward Talia Walton. "It was a lot of fun to be out there. We knew it was going to be hard, but we wanted it. We really wanted it."
Chiney Ogwumike, the Pac-12's leading scorer, had 23 points but was held in check for most of the game, and her teammates were unable to pick up the slack. The Cardinal especially had trouble from long-range, shooting 9 for 41 on 3-pointers.
"I thought we slowed them down just enough, and we made them work just enough," Washington coach Mike Neighbors said. "They could have easily gone 15 of 41 and we would not be sitting here, but they didn't."
Mikaela Ruef set career highs with 16 points and 22 rebounds, and Bonnie Samuelson scored 14 for Stanford, which last lost to Washington Dec. 22, 2005, in Seattle.
Washington led 85-73 with less than a minute to go when Stanford started a desperate attempt at a rally. Four straight missed free throws for Washington opened the door as Bonnie Samuelson hit a 3-pointer with 39 seconds to go to start the flurry and then another 3-pointer by Samuelson with 9 seconds left cut the lead to 85-81. The Huskies were called for a 5-second violation on the inbound, and with 7.8 seconds Ogwumike made one of two free throws to make it 85-82. Stanford nearly pulled off another steal on the inbounds pass, but it turned into a tie-up and Washington had the possession arrow. This time, William pulled in a long pass and was fouled for the final free throws.
"It was a little too little, too late," Ogwumike said. "We were really motivated to play toward the end, but the first 38 minutes we were a little lackadaisical on offense."
Stanford started cold - missing its first seven 3-pointers - and Washington took advantage to build a 14-4 lead in the first 4 1/2 minutes. The Cardinal came back to tie the score at 17 three minutes later, but even after that push the Huskies were able to hold the lead for most of the first half, going into halftime leading 41-34.
Plum had a lot to do with the Huskies' strong first half, taking the offensive spotlight away from Ogwumike. Plum scored 15 in the first half and was 3 for 3 from 3-point range.
Washington kept Ogwumike mostly bottled up while building their halftime lead. The Huskies packed the paint against the Pac-12's leading scorer, and Ogwumike was held to eight points on seven shots before halftime. UW mostly kept the ball out of Ogwumike's hands, as the forward didn't attempt a free throw until 1:35 left in the first half.
The Cardinal came out in the second half with a clear directive: get Ogwumike the ball. She scored Stanford's first nine points of the half, outdoing her first-half point total in the opening 3 1/2 minutes.
But despite Ogwumike's quick outburst, the Cardinal couldn't get a consistent offense going, too often settling for a long 3-pointer which mostly didn't go in.
Meanwhile, Washington's offense was rolling. A 16-2 run gave the Huskies a 64-48 lead with 9 1/2 left to play, and the Cardinal didn't find an answer until it was too late.
The Huskies have struggled at times this season and had lost three of five going into Sunday's game, but after the upset they have their sights set high.
"Winning this game boosted our confidence to the max," Walton said. "If we can play with Stanford, we can play with anybody when we play together. Now that we see what we can do, we're going to be ready for whoever else steps on the court."