Danny McClintick had a game-high four goals, but Gordon Marshall netted the game-winner.
Danny McClintick earned NCAA Tournament MVP honors after scoring four goals in the title match.
Cristiano Mirarchi led all scorers with three goals while Garrett Danner registered 14 saves.
The Bruins face hosts and fourth-seeded UC San Diego on Saturday in the first semifinal (1:00 PM).
Cristiano Mirarchi discusses his most memorable moment at UCLA, beating USC to win 2011 MPSF title.