SAN JOSE, Calif. – Given the best possible NCAA Tournament path to a home-state Final Four appearance, the Arizona Wildcats dropped the ball Thursday night.

Or, rather, couldn’t shoot the ball well enough to keep from blowing an eight-point lead in the final four minutes.

Second-seeded Arizona was upset 73-71 by 11th-seeded Xavier in the West Regional semifinal on Thursday while allowing the Musketeers to shoot 52.8 percent and missing three key shots in the final minute that might have tied or won the game.

BOX SCORE: No. 11 Xavier 73, No. 2 Arizona 71

After Dusan Ristic missed a heavily contested 10-footer with 51 seconds left and Sean O’Mara scored inside to give Xavier the final two-point lead with 22 seconds left, Kadeem Allen missed a 15-foot jumper and Allonzo Trier missed a three-pointer with eight seconds left at SAP Center.

Each of those shots was at least somewhat contested by Xavier’s ever-changing defense, so it was the Wildcats’ defense that stuck heavily in the mind of UA coach Sean Miller. Not only did the Wildcats struggle to defend the crafty Musketeers much of the game, but they most critically allowed 3-pointers by Trevon Bluiett and Malcolm Bernard in the final 3:25 that put Xavier back in the game.

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“When you have teams fighting to stay alive, you have to jump,” Miller said. “You have to run at them. You have to close out with great effort. You have to make them miss.”

They didn’t. The Wildcats only missed their shots, surprisingly even getting the last miss from Trier, who was so hot in the middle of the second half that he scored 15 straight points after a cold first half.

But just getting the Wildcats in a position to take the eight-point lead, and maybe advance to the West Region final, wasn’t enough for the hyper-competitive Trier. He was upset about the last miss, and the loss, and wasn’t about to consider anything else.

“We just lost the game,” Trier said. “There’s no other way to put it.”

The loss ended UA’s season at 32-5, while Xavier moved to 24-13 and into a region final Saturday against Gonzaga for a spot in the Final Four. For the Musketeers, the win avenged their 68-60 loss to Arizona in the 2015 Sweet 16.

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“It feels good just to be able to kind of get that revenge that we have been looking for,” Bluiett said. “And, two, just to make it to the Elite Eight. It’s been a while since the program has done it. And just to get back there it’s a surreal feeling.”

It was only the third time Miller has ever lost to a lower seeded team in the NCAA Tournament, but the second straight year, after sixth-seeded Arizona was bounced by 11th-seeded Wichita State in the first round last season.

Bluiett led Xavier with 25 points on 9-for-17 shooting, scoring 18 of his points in the first half.

Trier finished with 19 points while Ristic had 17. Lauri Markkanen had nine points and eight rebounds but only took nine shots, many of which were closely guarded by Xavier’s ever-changing defense.

“They played really well defensively,” Markkanen said. “I did not get a good shot. They’re a really good team.”

Arizona built its eight-point lead with 3:44 remaining but a 7-0 run pulled Xavier into a 71-71 tie entering the final minute. After Ristic missed his 10-footer with 51 seconds left, Bluiett had the ball at the top of the key – but instead of driving or popping a 3, he sharply passed under the basket to O’Mara who made what became the game-winning layup.

“Fortunately, Sean was able to catch a great pass by Tre and put it in,” Xavier coach Chris Mack said.

UA had trouble at times throughout the game. The Wildcats trailed by two points entering the final seven minutes, but went on a 12-0 run to take a 67-61 lead, getting 3-pointers from Trier and Kadeem Allen during the run. Two free throws from Parker Jackson-Cartwright gave UA its eight-point lead before Xavier made its stretch-run comeback.

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After Arizona took a two-point halftime lead, Xavier had gone on a 7-0 run early in the second half. The Musketeers hit 6 of 8 shots immediately after halftime, prompting Miller to call a timeout with 15:22 left.

UA went on a 7-0 run to take a 52-48 lead, but with 13 minutes to go, Allen and Bluiett were called for offsetting technical fouls after they had an animated conversation.

After the technicals, Bernard hit a 3-pointer and Quentin Goodin dunked to put Xavier back ahead 53-52 entering the final 11 minutes.

At the end of the first half, Rawle Alkins hit a 12-foot jumper just before the halftime buzzer to give Arizona a 37-35 halftime lead.

Alkins, who was playing with a broken index finger, missed his first four shots of the half.

He said the finger didn’t bother him throughout the half, and tried to be upbeat afterward.

“We had a great year, and it just takes one loss for everyone to forget what we did all year,” Alkins said. “We won the Pac-12 championship, the Pac-12 Tournament, and 32-5. We had a historic year for the team.

“Of course we wanted more. But overall, it was a good season.”