The win puts CSUDH (45-13) one victory away from an automatic berth into the NCAA Championships. UCSD (39-21) must win back-to-back games on Saturday in order to advance.
After UCSD jumped out to a 3-0 lead on an RBI triple by Kirsten Willmon and a two-run single from Maria Sykes in the top of the third inning, CSUDH capitalized in its half of the frame on a pair of Triton fielding errors and Veronica Vazquez's two-run double.
"Today was very disappointing. I say it all the time, it comes down to pitching and defense," said UCSD head coach Patti Gerckens. "We lost this game with one bad inning, and it was very bad. We have to come back stronger tomorrow. We absolutley can do that, [our players] know it and we've done it before."
Kris Lesovsky led off the third with a double to right center and was brought in by Willmon's triple to nearly the exact same spot. UCSD put runners on first and third with one out, but CSUDH caught Willmon at home on Mya Romero's attempted squeeze bunt for the second out of the inning.
Sykes responded with a hard single to center, driving in Romero and Caitlin Brown to put UCSD up by three.
CSUDH was granted a runner with one out in the third inning, as UCSD starter Camille Gaito (27-10) mishandled a slow roller to the circle by Jackie Reyes. Gaito hit Khryssi Steele to put two runners aboard before Vazquez brought Reyes and Steele home with a two-bagger to left center.
Vazquez moved to third on Jessica Hall's single up the middle and scored on an RBI single by Stephanie Jimenez to make it 3-3.
With two outs and runners on first and second, Gaito forced Daisy Beltran to pop a ball high in the air in front of home plate. However, confusion between Gaito and first baseman Nicole Spangler allowed the ball to drop just inside the foul line, giving Jimenez enought time to come around from second to make it 4-3.
Jimenez (26-5) took over for Lauren Harper in the circle the next half inning and held the Tritons to just a pair of hits and no walks the rest of the way.
Spangler nearly tagged Jimenez for a home run in the top of the sixth, but the ball hit the top of the wall and fell for a double. UCSD was unable to take advantage of the runner in scoring position as Jimenez got Monique Portugal to foul out and Emily McQuaid to ground out to end the inning.
Willmon was 3-for-4 with a run in the game, while Sykes was 1-for-3 with two RBI. Gaito worked all six innings for UCSD, limiting CSUDH to five hits and two earned runs.
UCSD had an opportunity in the top of the first to put runs on the board, but Harper did well to escape unscathed. Willmon singled with one out and moved over to second on Charly Swanberg's two-out single. Romero singled up the middle, but Willmon was held at third to load the bases. Harper fell behind to Sykes, but got the Triton freshman to look at strike three to keep the score 0-0.
"We've not done anything easy this year. The way we're looking at tomorrow is that it's a regular doubleheader and we have to play better. We beat ourselves," said Gerckens.
The Tritons fell in their opening game of the NCAA Tournament last Friday against No. 3-seed Dixie State, but rebounded for four straight victories to take the West Region II title. UCSD also had three errors in the loss against DSC.
CSUDH and UCSD will meet again at 11:00 a.m. on Saturday morning. If UCSD wins, the Tritons force a winner-take-all game for the West Super Regional title a half-hour after the completion of game one.
CSUDH is 28-0 this season at Toro Diamond.