LUBBOCK, Texas -- Texas Tech scored two runs in the first two frames and Cara Custer kept the Oklahoma State bats at bay long enough for the 24th-ranked Red Raiders to close the regular season with a 2-1 victory Monday at Rocky Johnson Field.

The win helped Tech (40-15; 13-10) claim its fourth Big 12 series of the year while also reaching the 40-win mark for the second consecutive season and the third time in program history.

The Red Raiders can now finish no worse than fifth in the conference standings, which marks the school's highest finish since tying for third in 2001.

"I just expected to have a good team this year," Tech head coach Shanon Hays said. "I didn't think about numbers exactly because our schedule was so much better than it's been the last two years. We played good teams all the way through and that's why we have such a good RPI. To be on the plus side of the Big 12, it feels really good."

Unlike its Saturday outing against OSU starter Kat Espinosa, Tech jumped on the right-hander early as Adriana Perez hit a sacrifice fly to right field in the first that scored Logan Hall.

Espinosa, who shut out the Red Raiders in the opener, gave up her final run an inning later when Raven Richardson dropped a single into right field to score pinch runner Kermitria Ward.

Ward used her speed to frustrate the Cowgirls through most of the middle innings as the sophomore had a season-high two stolen bases. She set up Richardson by swiping second base and then moved to third on a Taylor Woodall throwing error from the plate.

Richardson's single was one of only three hits against Espinosa (15-11), who struck out two and walked three in the complete-game effort. Mikey Kenney had a one-out single in the first to help spark the early run while Katelyn Williams had a two-out single up the middle in the sixth.

Even with less than staggering numbers at the plate, Custer (25-10) was effective in keeping the Cowgirls off the scoreboard as the freshman worked around five hits and six walks to give up only a run with nine runners left on base.

Her only blemish was a two-out RBI single from Chelsea Garcia in the fifth that was just far enough to Richardson's right to keep Tech from getting out of the inning. The Cowgirls had previously loaded the bases in the third, only for Custer to get out of the jam by forcing Garcia to fly out to Ashley Hamada in right.

The complete game was the 17th of the season for Custer, who helped Tech improve to 72-2 under Hays when taking a lead into the seventh inning.