Pusica, a freshman reserve guard from Serbia, was 4 of 4 from the floor, including both 3-point attempts, and 6 of 6 from the line.
San Diego (11-11, 4-6 West Coast) led by 10 points at the break 32-22, as neither team lit it up in the first half. Santa Clara made just 6 of 25 shots and went over eight minutes without scoring at one point, while San Diego had a 4 1/2 minutes scoreless stretch.
Santa Clara was down 10 with 32 seconds left, but made three straight baskets - including Brandon Clark's 3-pointer - to cut it to three with 22 seconds remaining. But Johnny Dee and Thomas Jacobs were 4 of 4 from the line to seal the win.
Clark led Santa Clara (11-11, 5-5) with 22 points.