Penn State held the early lead, but two late runs, including one in the bottom of the seventh inning, gave Pacific a 2-1 victory in the opening game of a doubleheader Tuesday.
The second game was played late Tuesday night.
A Macy Jones bases-loaded single in the top of the first inning brought home Alicia Walker with the lone Nittany Lion run. Penn State (8-10) managed just six hits off Dani Bonnet, who struck out three and walked two in the complete-game effort.
Nicole Zapotoczny hit a fifth-inning solo home run to tie the game and Sydney Lahners bases-loaded infield single brought home the winning run with out one in the seventh.
Jessica Cummings pitched three innings of relief and took the loss, giving up four hits, one walk and both runs.