Cardell Butler made a three-point basket and Mark Brown made eight consecutive free throws in the final minute of overtime to help the Aggies to an 89-83 quarterfinal victory at the Anaheim Convention Center.
Utah State (22-8) will play UC Irvine in tonight's semifinals. Irvine beat Utah State twice in the final seconds.
Led by Ralphy Holmes, Fullerton (10-19) pulled off an amazing rally to force overtime.
Trailing, 71-66, Holmes made a three-point basket with 30 seconds left. Toraino Johnson of the Aggies raced to the other end but missed a layup and Holmes grabbed the rebound.
The sophomore guard then made a jump shot to tie the score with 21.5 seconds left.
Utah State's Desmond Penigar missed a shot on the Aggies' final possession in regulation.
UC Santa Barbara 53, Pacific 44 -- The top-seeded Gauchos struggled mightily, but Branduinn Fullove's three-point shot with two minutes left helped pull the defending tournament champions into the semifinals.
Fullove's 25-foot shot was part of a late 7-0 run that gave Santa Barbara (18-12) breathing room. The Gauchos then made eight free throws in a row to put away the scrappy Tigers.
"I saw the clock was winding down and the ball was coming around, so I got my feet ready," Fullove said. "I was just fortunate enough to step up and knock it down."
Fullove, the league's player of the year, scored a game-high 20 points and Mark Hull added 12. Hull made consecutive three-point baskets and Chrismen Oliver added one in a 11-0 second-half run that gave Santa Barbara a 36-31 lead.
The Gauchos made one of their first 11 shots and only four of 24 and trailed, 21-16, at intermission. To compensate for the atrocious shooting, they held Pacific to 32.6% from the field. The Tigers (12-16) made only one of 16 three-point tries.
"Good basketball teams have to find a way to win without shooting the ball well," Gaucho Coach Bob Williams said. "I hope we did get it out of our system."
Cal Poly San Luis Obispo 54, Idaho 50 -- Junior forward Varnie Dennis scored 10 of his game-high 17 points in the second half as the Mustangs (15-13) recorded their first tournament victory in three tries.
Jered Patterson broke a 50-50 tie with 22 seconds left and Dennis came up with a steal on the next Idaho possession. Steve Geary made two foul shots with five seconds left to secure the victory.
Shane Schilling added 15 points and Jason Allen added 11 points and 10 rebounds for Cal Poly. Rashaad Powell led the Vandals (13-15) with 16 points.