LAS VEGAS -- The defending Pac-12 Tournament champions vs. the preseason conference favorites.

Fifth-seeded Colorado will play No. 4 Arizona in the quarterfinals on Thursday here at the MGM Grand Garden Arena (3:30 p.m., Pac-12 Network).

The Buffs, coming off a 74-68 victory over Oregon State in the opening round, feel like they deserved the bye.

As everyone knows by now, Sabatino Chen's game-winning 3-pointer in Tucson on Jan. 3 was taken away by the officials.

CU had to settle for a split of the regular-season series.

"Yes, we do," Spencer Dinwiddie said when asked if the Buffs' 93-83 loss at Arizona should have been another quality win over a ranked foe. "We don't go back and we don't cry over spilled milk. We know it goes in the record book as a loss, but a lot of people around the country have the same feeling we do."

Most "bracketologists" feel the Wildcats (24-6), ranked No. 18 in this week's Associated Press and USA Today/Coaches polls, are a lock for the NCAA Tournament.

The Buffs (21-10) -- who punched their ticket last season by beating Arizona in the Pac-12 Tournament championship -- believe they have also earned an at-large bid.

But why take any chances on Selection Sunday?

"It's definitely less pressure, but we're in it to win it," Andre Roberson said of the Buffs' mindset entering the conference tournament.

CU, which is 4-2 against ranked teams, beat the Wildcats 71-58 on Feb. 14 at the Coors Events Center.

"It's always fun playing Arizona," Jeremy Adams said. "I guess they're still ranked in the top 25, so that's definitely an important game and hopefully we get a win."

Scott steps up

Roberson was "rusty" after missing the final two games of the regular season with a viral illness and the nation's leading rebounder was limited to seven minutes in the first half after being whistled for two quick fouls.

Josh Scott picked up the slack, grabbing eight of his 10 rebounds before the intermission. The 6-10 freshman pulled down six rebounds in the first five minutes, which helped the Buffs seized an early 11-6 advantage on the scoreboard.

"We need Josh to play well, much like we need (Askia Booker) to play well, for us to be as good as we are capable of being," CU head coach Tad Boyle said. "I was proud of his rebounding effort.

The Buffs, out-rebounded by six during the 64-58 loss to Oregon State last Saturday in Boulder, had a 43-30 edge in the rematch.

The 'X' factor

According to Boyle, talented freshman Xavier Johnson let the officials and the Beavers' big men get in his head during the regular-season finale.

But four days after a forgettable performance, Johnson turned the tables on Oregon State with 16 points and eight rebounds.

"That's something I'm going to have to work on myself ... my mental focus," Johnson said. "Coach has helped me a lot with that and I'm getting better."

"He was much better," Boyle added.

Spark off the bench

After Roberson was whistled for his second foul Eric Moreland (14 points, 13 rebounds) started to have his way inside.

The Beavers capped an 8-0 run with a 3-pointer by Challe Barton to take a 14-11 lead.

Adams sparked CU with eight points off the bench, including a 3-pointer that gave his team a 23-16 advantage with 6:07 remaining in the half.

"I thought Jeremy Adams gave us great minutes in the first half, made some shots," Boyle said. "He's a lock down-type defender. I think I'd put him in there with (Sabatino Chen) and Spencer (Dinwiddie) and Andre (Roberson) in terms of his understanding of our defensive concepts."

Notable

CU leads the series 9-4 after winning the first meeting between the programs on a neutral court (Buffs are 6-1 in Boulder and 2-3 in Corvallis). ... The Buffs have held their last 11 conference opponents under 70 points. ... Boyle is 5-0 in the Pac-12 Tournament and 9-1 in his last 10 neutral-court games at CU.. ... This is the fifth time in school history that CU has reached 21 wins.

Quotable

"I heard Sab say, 'That looks good,' and I was like, 'It does.' And then it went in," Dinwiddie on his half-court buzzer-beater that gave CU a 32-26 lead at the intermission.

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