Tyler Buffett limited Arizona to three hits over eight innings, and Oklahoma State took command of its bracket in the College World Series with a 1-0 victory Monday night.
The Cowboys, who beat UC Santa Barbara by the same score on Saturday, became the first team in the CWS' 70 years to win back-to-back 1-0 games.
Buffett (9-3) allowed three singles in the first five innings, walked two and struck out six. Trey Cobb took over in the ninth and earned his sixth save.
Oklahoma State scored in the fourth when Donnie Walton doubled and came home on Garrett Benge's single. Otherwise, Buffett and Arizona starter Bobby Dalbec (10-5) matched zeroes through eight innings the same way the Cowboys' Thomas Hatch did with UC Santa Barbara's Shane Bieber on Saturday.
The Cowboys (43-20) on Friday can clinch a spot in next week's finals with a win. Arizona (45-22) plays UC Santa Barbara in an elimination game Wednesday.
