Buffalo guard Wes Clark scored 25 points and Jeremy Harris had 23 points and seven rebounds as the 13th-seeded Bulls pulled off the biggest upset on the first day of the NCAA Tournament, an 89-68 blowout victory over fourth-seeded Arizona on Thursday at Taco Bell Arena in Boise, Idaho.

CJ Massinburg had 19 points and six rebounds, and Nick Perkins scored all of his 13 points in the second half for the Bulls (27-8). Buffalo set a school record for victories and earned its first NCAA Tournament win in its third trip in the past four seasons.

Buffalo, the Mid-American Conference champion, will face fifth-seeded Kentucky in the second round of the South Regional on Saturday.

Massinburg sank five 3-pointers and Clark, Harris and Nick Perkins had three apiece. Massinburg's third 3-pointer with 9:46 remaining in the game gave the Bulls a 70-57 lead, and the margin just kept growing.

Dusan Ristic had 16 points, Deandre Ayton had 14 points and 13 rebounds, and Allonzo Trier had 10 points for the Wildcats (27-8). Arizona had won five in a row and eight of nine while winning the Pac-12 regular-season and tournament titles.

The Wildcats ended the season under a cloud of suspicion as coach Sean Miller denied allegations that he paid $100,000 to make sure Ayton would enroll at Arizona.

The game matched two of the highest-scoring teams in Division I -- Buffalo entered ranked seventh with a 84.8 scoring average and Arizona was 41st at 80.9 -- but the Bulls were the more aggressive team and took control in the second half behind their guard play.

The Bulls shot 54.8 percent from the floor and made 15 of 30 3-point attempts. The Wildcats hit 45.3 percent of their field-goal attempts, including just 2 of 18 from 3-point range.

Ayton, a freshman considered a potential top pick in the NBA draft if he forgoes his remaining eligibility, could not duplicate the dominance he showed in the final two games of the Pac-12 tournament, when had 64 points and 32 rebounds. Ayton tied Kevin Love's Pac-12 freshman record with 23 double-doubles.

Trier, who averaged 18.4 points a game, ended the season in a shooting slump, making 19 of 63 field-goal attempts (30.2 percent) and 6 of 35 3-point tries (17.1 percent).

The loss ended a dismal showing for the Pac-12 teams in the tournament. UCLA and Arizona State, both No. 11 seeds, lost in play-in games. They were the only other two conference teams in the tournament.

--Field Level Media