Nicholas converted all five of his 3-point attempts and finished with 21 points, while Riley was 4 for 5 and had 17 points for the Pilots (9-16, 2-8 West Coast), who were 11 for 16 as team from beyond the arc and shot 56 percent overall from the field. Both of Portland's conference wins this season have come against Loyola Marymount (8-15, 1-9).
Anthony Ireland scored 21 points for the Lions, who lost despite shooting 47 percent and making 5 of 9 3-point attempts.
Portland led 60-58 with 1:52 remaining but got a 3-pointer from Nicholas that sparked a 9-2 game-ending run.
Washington State's trio of Josh Hawkinson, Conor Clifford and Ike Iroegbu have withdrawn from the NBA draft and will play their senior season with the Cougars.
Gonzaga center Przemek Karnowski, who missed most of last season with a back injury, says he is returning for another year.
Wisconsin forward Nigel Hayes has withdrawn from the NBA draft and will return to the Badgers for his senior season.