Hatch scored eight consecutive points to give the Tritons a 64-63 lead with 1:26 left to play, but the Warriors answered with an 8-2 run to claim the victory and hand UCSD its seventh defeat in eight games.
Reggie Jones and Evan Scott scored 18 points apiece for Cal State Stanislaus, which led by as many eight points in the second half before UCSD's comeback in the final three minutes. The Warriors improve to 9-12 overall and 7-10 in California Collegiate Athletic Association play with the win, which snapped a two-game losing streak.
UCSD, which entered Thursday's contest a game out of eighth place in the conference standings, falls to 10-13 overall and 5-12 in the CCAA. The Tritons are just 2-5 in their last seven home games.
"We just didn't really execute down the stretch the way we would have liked," head coach Chris Carlson said. "We did some good things, but there were a couple of times that we didn't execute and a couple of possessions defensively when we didn't chase down long rebounds and it hurt us in the end."
Hatch, who has developed into one of the conference's elite centers this season, scored 19 of his 28 points in the second half to put UCSD in a position to win down the stretch. He was 11-for-16 from the field and hit 6-of-8 free throws to eclipse his previous high of 26 that came in the Tritons' double overtime win over Cal State L.A. on January 13.
In addition to reaching the 20-point mark for the third straight game for the first time in his career, the Henderson, Nev. native also finished with four rebounds and two assists in 32 minutes.
James McCann, who came off the bench for the first time this season, finished with 10 points on 2-of-7 shooting, but no other player scored more than nine points for the Tritons. Casey Ryan, UCSD's second-leading scorer, finished with just two points, but did corral a game-high 11 rebounds.
UCSD trailed 40-32 following a jumper by Jones four and a half minutes into the second half, but chipped away at the lead and came back to tie it at 48 following a three-point play from Justin Brue and consecutive baskets from Hatch.
The Warriors would score seven of the next eight points to take a 55-49 lead with seven minutes left and Prince Abidoye's three 30 seconds later made it 58-51 in favor of the visitors.
With Stanislaus in front 61-56 with 3:46 left to play, Hatch took over, scoring 10 straight points for the Tritons and eight in a row overall to give UCSD its first lead since midway through the first half. His layup with a minute and a half left put the Tritons in front by one, 64-63.
The lead wouldn't last long though, as Jones got to the rim on the Warriors' next possession, giving the lead right back to visitors with 1:01 left to play. McCann's layup missed the mark on UCSD's ensuing trip and Scott drew a foul and hit a pair at the line to put the Warriors in front by three at 67-64 with 38 seconds left.
Trailing by the same margin at 69-66 with 23 seconds remaining, the Tritons had one final chance, but Tyler McGrath's deep three was a touch too long and the Warriors closed out the five-point win.
Cal State Stanislaus shot just under 44% for the game, while UCSD finished at a 43% clip. The Tritons held a 38-28 rebounding advantage, but the Warriors connected on 10-of-21 attempts from the three-point line, 48%.
UCSD will look to pick up a victory in its final home game of the season on Saturday night against Chico State. Tip-off is slated for 7:30 p.m. at RIMAC Arena.