Marin Mornar's dunk gave the Lions a 17-9 lead with 11:37 left in the first half. The play ignited Portland (7-7, 1-0), which used a 25-2 run to take control of the game.
Pressley hit three 3-pointers and a layup during the run which lasted just more than eight minutes. Presley shot 7-for-13 from behind the 3-point arc. D'Marques Tyson hit a 3 just before the half ended to make it 46-26.
After the break, Pressley hit a 3, Gabe Taylor scored a layup, Pressley hit two free throws and Alex Wintering's jumper pushed the lead to 55-31 with 16:39 to play.
Brandon Brown scored 16 points and had six rebounds to lead Loyola Marymount (7-5, 0-1).