Oklahoma State scored two runs in the bottom of the ninth inning to defeat Oregon, 5-4, Saturday at the OSU/Tulsa Invitational in Stillwater.
Chelsea Alexander's RBI single was the game-winner after Sydney Pennington tied the game 4-4 with an RBI single earlier in the frame.
Earlier Saturday, the Cowgirls (11-5) defeated Louisville 2-1 in eight innings.
![Oklahoma State's Chelsea Alexander (55) drives in a run in the fourth inning of the Stillwater Regional NCAA softball tournament game between Oklahoma State University (OSU) and Tulsa in Stillwater, Okla., Saturday, May 18, 2019. Oklahoma State won 2-1. [Bryan Terry/The Oklahoman]](http://cdn2.newsok.biz/cache/large960_blur-d2c0047ea4f2e77f3e4aa1012f12f30b.jpg)