Waldow had 13 rebounds -- including seven offensive boards -- as Saint Mary's (15-5, 5-2 West Coast) out-rebounded Pepperdine (12-9, 5-4) 41-34. Kerry Carter added 18 for the Gaels, while Beau Levesque had 13.
Brendan Lane led Pepperdine with 18 points.
Saint Mary's jumped out early, using an 8-0 run to go up 13-5 at the 13:10 mark of the first half, en route to a 40-35 lead at the break.
Pepperdine pulled within one early in the second half on Jeremy Major's 3-pointer, but Saint Mary's pushed back with a 12-3 run. The Waves cut it to two at 62-60 with 7:15 left, but they never could get over the hump, as Saint Mary's made 13 of 18 free throws from that point to seal the win.