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.
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Jessica Cummings pitched three innings of relief and took the loss, giving up four hits, one walk and both runs.