Pineiro was 11-of-16 shooting, including 3 of 4 from 3-point range and grabbed eight rebounds. Isaiah Wright had 11 points and Tyler Williams scored 10 for San Diego (10-3). The Toreros have won five of their last six.
Ahmed Ali slipped a bounce pass to Robert Franks for a layup and, after a USD turnover, Ali drove the lane for another to pull the Cougars within one. After Pineiro missed the front end of a 1-and-1, Franks made 1 of 2 free throws to make it 74-all with 2:29 left but Pineiro answered with a dunk that sparked an 8-1 closing run as WSU missed its last four field-goal attempts.
Franks had 22 points for Washington State (7-4) and CJ Elleby added 13 with nine rebounds. Franks has 1,002 career points, becoming the 37th player in program history to top the 1,000-point plateau.
San Diego will play Drake in the championship game Sunday.