The result was hardly novel for the Anteaters (24-9 ranked No. 17 by the National Collegiate Baseball Writers' Assn.), who are now 15-0 at Anteater Ballpark. They have won 16 straight at home, dating back to last season.
UCI is also 6-0 in Tuesday games this season.
The Toreros (10-24) scored in the top of the 12th to take a 7-6 lead.
The San Diego rally, off of UCI closer Brian Hernandez, began with a two-out walk. Zach Sullivan then doubled into the left-field corner and Corey LeVier motored around from first to beat the relay throw to the plate.
Hernandez, however, helped himself improve to 3-0 by singling with two outs to set the stage for Hillman. Pierce Bily pinch ran for Hernandez, but only needed to trot home when Hillman's drive barely cleared the fence in left.
UCI scored five in the eighth inning to erase a 5-1 deficit, capitalizing heavily on some Torero benevolence.
D.J. Crumlich singled to open the UCI eighth and, one out later, he went to third on Hernandez's single.
Hillman followed with a run-scoring ground ball to shortstop and Christian Ramirez doubled in a run, then went to third on an errant relay throw to the plate.
Jordan Leyland and Tommy Reyes walked to load the bases.
Ronnie Shaeffer then swung and missed a 2-2 pitch under his hands, but the ball escaped the grasp of the catcher for a passed ball, allowing Shaeffer to reach and a run to score to make it 5-4.
Pinch-hitter Jon Hurst then walked to force in the tying run and Crumlich plated the go-ahead tally with an infield single into the shortstop hole.
The Toreros answered with a run in the eighth and the 'Eaters' pitching and defense stepped forward to keep things knotted.
Leyland, playing first base, leaned over a tarp in foul territory to catch a foul pop to end the San Diego eighth.
After Dillon Checkal's shallow fly to center skipped under a diving attempt by UCI's Ramirez, Shaeffer turned a blown squeeze play into a double play.
Shaeffer sprung from his crouch and to pounce on a soft bunt right in front of the plate. Shaeffer ran down the runner who had stopped about two-thirds of the way home, tagging him out. He then wheeled and threw to first and appeared to get the benefit of a blown call when the first-base umpire called the runner out.
UCI stranded a runner in scoring position in the ninth and 11th innings and had 11 hits, two shy of the Toreros' total, through 11.
San Diego opened the scoring with one in the fourth inning.
UCI answered in the fourth when Hernandez doubled, went to third on a Hillman single, then scored on a wild pitch.
After UCI left the bases loaded in the fifth, San Diego scored twice in the sixth. The visitors added two more in the seventh.