With the loss, Saint Mary's drops to 4-4-5, 3-1-2 West Coast Conference, while Portland improves to 6-6-2, 1-4-1 WCC.
"I felt we did not show up with the right mentality today," said head coach Adam Cooper. "We gave up three goals on set pieces... we need to regroup and get ready for the second-half of the season."
The Gaels had scores by Jose Cabeza, who floated in a free kick from 40 yards out. Trevor Newquist also scored for the Gaels on a header off a corner kick from Riley Hanley.
Portland got on the board first in the 28th minute taking a pass from Ben Hemphill and scoring from 15 yards out. The goal was SMC's first goal allowed of the conference season.
After a Pilots foul in the 38th minute, Cabeza lined up a free kick from 40 yards out. Cabeza floated the kick into the box as the ball kept drifting and drifting, finding it's way over teammate Malcolm Alugas and the UP goalie into the net. The match would remain tied at 1-1 at halftime.
The Gaels held an 8-3 edge in shots in the first-half and took both corner kicks of the half. In the second half, Newquist scored with a header in the box off a corner kick from Hanley in the 51st minute.
Portland would come through with the tying goal in the 63rd minute, and the go-ahead in the 83rd minute. Colin Anderson had assists on both scores.
The Gaels could not come away with the equalizer as the Pilots handed the Gaels their first loss of WCC action.
Saint Mary's has a bye this upcoming week and will next face Portland at Portland on October 28.