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Jae C. Hong, Associated Press
Colorado's bench reacts to a play during the second half of an NCAA college basketball game against Arizona in the finals of the Pac-12 conference championship in Los Angeles, Saturday, March 10, 2012.

LOS ANGELES — Freshman Spencer Dinwiddie scored 14 points, Carlon Brown added 13 and Pac-12 newcomer Colorado upset Arizona 53-51 Saturday to win the league's tournament championship and earn the school's first NCAA tournament bid since 2003.

The Buffaloes (23-11) became the first No. 6 seed to win the tournament title since Southern California in 2009 by winning four games in four days, the first time Colorado has done that in the program's 111-year history. The Buffs, who left the Big 12, were playing in their first tourney final since 1990, when they lost to Oklahoma for the Big Eight championship.

Kyle Fogg scored 14 points, but his off-balance 3-pointer to win missed at the buzzer for fourth-seeded Arizona (23-11) in what may have been the league's last tourney at Staples Center. After 11 years, the event could be moved to Las Vegas.

Frontcourt mates Solomon Hill and Jesse Perry had teamed with Fogg to score 50 of Arizona's 72 points in a semifinal win over Oregon State. Hill came on stronger in the second half and finished with 13 points, while Perry added 11 in their team's second straight year in the tourney final.

The Buffs lack any tradition in their new conference, but they didn't lack fans. Their student section, flown in by the school, was loud all week, and they proudly displayed a homemade sign reading Welcome to Coors Event Center West.

Brown rewarded the Buffs' backers with 48 seconds left. The senior from nearby Riverside, Calif., powered around Jordin Mayes and slammed down a one-handed windmill dunk, eliciting raucous cheers as Arizona called timeout.

Hill's layup drew the Wildcats to 53-51 with 20 seconds left. Buffs senior Austin Dufault missed two free throws with 14 seconds to go, giving Arizona a final chance to win. But Fogg's shot was left of the basket and time expired, setting off a wild celebration on court.

Colorado opened the second half on an 18-8 run, with Dinwiddie and Brown combining for 10 points, to extend the Buffs' lead to 48-36. Fogg, Hill and Perry accounted for all of Arizona's points.

Buoyed by their experienced trio, the Wildcats outscored the Buffs 9-2 to close to 50-45.

Both teams struggled at the start, combining to miss 15 of 21 shots. The Buffs led most of the half, although not by more than five, before Arizona took its first lead with 5:56 to play in the half on a 3-pointer by Fogg. The Buffs were up by two at the break and they stretched their lead early in the second half.

The Buffs have notched 47 wins in two seasons under coach Tad Boyle.