Andrew Bock put up a team-high 18 points for Pacific (16-15), which will await its second-round opponent as the tournament reseeds. Sama Taku added 15 points for the visitors.
For Grand Canyon (15-15), Killian Larson tallied 20 points and 11 rebounds, Daniel Alexander also scored 20 on 6-of-10 from 3-point range and Jerome Garrison pitched in 13 points.
Grand Canyon shot a stellar 45.8 percent from the field in the first half, including 7-of-13 from beyond the arc, as it took a 35-25 lead into intermission. Pacific made good on less than 40 percent of its field goal tries and sank just one 3-pointer.
The Tigers improved their field goal efficiency to 59.3 percent in the second stanza as they mounted their comeback. Trailing by 15 early in the frame, Pacific used a 20-5 run to tie the contest up at 49 with 9:39 to play. The teams exchanged blows down the stretch, and after the Antelopes tied the game at 67 on an Akachi Okugo 3-pointer with 1:30 left, the Tigers answered on their next possession when Gill made a layup off an offensive rebound to put them up by the final score of 69-67. Garrison missed a pair of free throws for Grand Canyon with 46 seconds left and he went on to miss the game-tying field goal attempt at the buzzer as well.
Pacific outrebounded Grand Canyon by a 33-26 margin and also won the turnover battle, 17-15.