Danny McClintick earned NCAA Tournament MVP honors after scoring four goals in the title match.
Danny McClintick had a game-high four goals, but Gordon Marshall netted the game-winner.
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.
Paul Reynolds, Gordon Marshall and Garrett Danner were all named to the First Team All-MPSF.
The Bruins are 8-2 against the 2014 NCAA field and enter with the nation's best record at 27-3.
Danny McClintick scored a team-high three goals to lead the Bruins (photo by John Hilinski).
Garrett Danner had 12 saves, but the Bruins' offense scored the fewest goals in six years.
Senior Daniel Lenhart led the Bruins with a hat trick against the Gauchos.
The Bruins will face the winner of No. 8 Pacific/No. 9 UCSB on Friday at 3:00 p.m. at Long Beach St.
Gordon Marshall scored four goals in the 16-8 win over No. 4 Long Beach State.