The Anteaters (7-6) bolted out from a 28-27 halftime lead with a 15-8 run that featured three 3-pointers by Nelson.
UC Irvine made 24 of 39 field goals, the 61.5 percent its best shooting of the season.
The Pioneers (5-6) came as close as four, 47-43 on a Bryant Rucker jumper -- his only bucket of the game -- with 10:50 to play. But UC Irvine scored the next eight points, including a McNealy 3 on a pass from Nelson. McNealy, a senior, was 6 of 11 from the field and has scored 982 career points.