Decker, a freshman, struck out and walked in her previous at-bats before hitting a bases-loaded triple in the fifth inning down the right field line. That sparked the come-from-behind win.
The loss was the second in a row for the Cowgirls and eliminated them from the eight-team field. OSU finished the season 42-20 in becoming the first team eliminated.
Decker's hit came off losing pitcher Kat Espinosa, who in five innings allowed nine hits and six runs. She walked two and struck out eight. Espinosa (23-10) got the first out in the fifth inning before Britt Vonk singled and Jace Williams doubled.Then, after an out, Espinosa walked Frani Echavarria to load the bases, setting the stage for Decker.
"I was really pumped up," Decker said. "We had bases loaded and two out.I just wanted to find a way to put the ball where no one was standing. The ball was up and inside and I was looking for it there."
With a 1-1 count, Decker hit the ball into right field, where OSU's Sammy Diffendaffer tried for a diving catch. The ball rolled to the fence and three runs scored. Decker scored moments later on an error by OSU shortstop Chelsea Garcia to give the Golden Bears a 5-2 lead.
California (45-12),which plays Baylor later Saturday in another elimination game, got another run in the sixth when Elia Reid homered to left field off Espinosa. It was Reid's ninth homer of the season and her 26th RBI.
Jolene Henderson threw the complete game for her 40th win of the season against nine losses. Henderson hit Mariah Gearhart on her first pitch of the game, then retired the next 10 batters before running into trouble in the top of the fourth inning. The Cowgirls got five consecutive singles to take a 2-1 lead. Tamara Brown and Ashley had the RBI singles.
Henderson fanned six and walked none.