BOULDER, Colo. (AP) - Hanging with the Arizona Wildcats for one half wasn’t going to cut it for Colorado this time.

About six weeks after watching a four-point halftime deficit in Arizona turn into a blowout, the Buffaloes went into the locker room trailing the Wildcats by five Saturday night and vowed not to let them get away again.

K.J. Simpson and Tristan da Silva led a second-half surge that carried Colorado to a 79-63 upset of the nation’s second-ranked team, matching the highest-ranked opponent ever beaten by the Buffaloes.

"Yeah, ’Bari said it in the locker room," da Silva said of teammate Jabari Walker. "We’ve been in this situation a few weeks ago at Arizona. And you know, we said to ourselves, we can’t let this happen again, basically.

"So, we went out there and gave it even more than in the first half. It paid off."

Fans stormed the floor after the Buffs (19-10, 11-8 Pac-12) snapped the Wildcats’ nine-game winning streak by outscoring Arizona 47-26 in the second half.

The loss by the nation’s second-ranked team added to a shocking Saturday in which top-ranked Gonzaga, No. 3 Auburn, No. 4 Purdue, No. 5 Kansas and No. 6 Kentucky all lost, as did No. 9 Texas Tech. The six losses by AP Top 10 teams in the same day matched the most ever.

Da Silva scored 13 of his team-high 19 points in the second half and Simpson scored all but one of his 13 points after halftime.

Arizona (25-3, 15-2) led 37-32 at the break, but the Wildcats’ leading scorer, Bennedict Mathurin, was held scoreless in the second half after scoring 12 points in the first half. Azuolas Tubelis led the Wildcats with 13 points.

The Buffs’ second win in 19 games all-time against No. 2 teams followed a dispiriting 82-65 loss to Arizona State on the same court 48 hours earlier.

"Come on, you knew they were going to play better," Arizona coach Tommy Lloyd said. "Their program has had a ton of success. They have a successful coach. They’ve got a ton of pride. (Colorado coach Tad Boyle) really challenged them and they were great.

"They were way more physical than us and got the game on their terms when they got that lead in the second half and were able to control the tempo and everything."

The Buffs held the ’Cats scoreless over stretches of 4:27 and 3:59 in the second half to secure their biggest win since beating No. 2 Oklahoma State 57-53 on Feb. 12, 1992.

"Boy, the difference between two nights," Boyle said. "You guys were here on Thursday. You saw how angry I was. And as angry as I was that night, I’m as proud tonight. Because, make no mistake, we beat a really good basketball team.

"And maybe Arizona was due for a letdown. I don’t know. I think we had a lot to do with that."

This marked the 23rd win against a ranked opponent in Boyle’s 12 years at Colorado and the 10th different season a Boyle-led Buffs team defeated a Top 25 opponent.

The Buffs opened the second half on a 17-7 run and never looked back. Walker and Keeshawn Barthelemy each scored 15 points and Evan Battey added 11 on his senior night as all five Colorado starters scored in double figures.

Mathurin had eight points, including a pair of 3-pointers, in a 10-2 run that erased Colorado’s early 16-11 lead. His breakaway dunk capped a 9-3 Arizona run that put the Wildcats ahead 33-27.

Mathurin, who came in averaging 17.3 points per game, missed all three shots he took in the second half and was whistled for a charge while driving to the basket with Arizona down 68-59 with less than four minutes remaining.

"Listen, this game at the end of the day really has no impact on anything," Wildcats coach Tommy Lloyd said. "Other that we got to get better and win or lose I would have said that.

"So, I mean, obviously, you know, we really haven’t even talked about the Pac-12 championship, because it’s all about the next game. And, you know, we didn’t rise to the occasion today. And we got a tough game Tuesday at USC."

SENIOR NIGHT

Battey told the crowd he wants to return to Colorado to coach some day and he was thrilled to cap his senior night with a huge win.

"Yeah, I was a mess pregame," said Battey, who’s played in the most wins (86) in program history. "I thought I was going to be more of a mess after the game, but I probably used up all my tears pregame."

BIG PICTURE

The Wildcats sank 13 of 14 free throws in the first half but were just 5 for 8 after halftime. They also missed 10 of their 11 3-pointers in the second half after sinking 4 of 7 before halftime.

POLL IMPLICATIONS

Arizona’s reprieve might be all the other top-10 teams that lost Saturday, but this one was a blowout. Their other two losses this season were by 77-73 at No. 19 Tennessee on Dec. 22 and 75-59 at No. 7 UCLA on Jan. 25.

UP NEXT

Arizona: Visits USC on Tuesday night before hosting Stanford and Cal in a busy week to close out the regular season.

Colorado: Wraps up its conference slate at Utah next Saturday night.

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