San Diego (15-15, 8-10 West Coast Conference) faces Pepperdine and Portland (16-14, 7-11) will play the No. 3 seed next Saturday in the quarterfinal round of the West Coast Conference Tournament at Las Vegas.
San Diego led 45-38 midway through the second half and used a 15-7 surge to make it 60-45 with 5:55 left. Portland pulled within 61-50, but the Toreros shot 17 of 20 from the free-throw line down the stretch to seal it.
Johnny Dee scored 12 points and Cameron Neubauer and Vasa Pusica chipped in 10 apiece for San Diego, which snapped its three-game losing skid.
Kevin Bailey scored 23 points and Alec Wintering had 21 with five assists to lead Portland, which has lost four straight.