It moves them on to the winner's bracket game against No. 2 Arkansas Saturday afternoon.
"We've been waiting for this moment for a while," said OU head coach Patty Gasso. "Team was ready to come out and attack early, and that's exactly what we did. So, everybody followed the game plan to a T."
Pitcher Keilani Ricketts got the scoring started with her three-run single to right.
A pair of errors allowed Ricketts and designated player Brittany Williams to score and make it 5-0.
Slugger Lauren Chamberlain then pounded her 26th homer of the year, a three-run shot into the left center bleachers to run the count to 8-0.
"First at-bat I was just working on seeing the ball in and just reading the spins, the speeds so I can relay that to the rest of my team," Chamberlain said.
OU added another in the second on center fielder Destinee Martinez's sacrifice fly.
The Sooners weren't done scoring yet, though.
They tallied another eight-spot in the third.
First, Ricketts reached on a bases-loaded walk for her fourth RBI of the contest.
Then, catcher Jessica Shults ripped a two-run single back through the box and Martinez slapped a bases-loaded infield single to run the count to 13-0.
Chamberlain smashed a two-run double into the left field corner a batter later to cap off the scoring.
"For the most part, just seeing the ball well, wanting to pass the bat to the rest of my lineup," Chamberlain said of her 3-for-4, five-RBI performance. "And overall it was just a really good team effort."
OU banged out its 17 runs on 13 hits, while pitching was solid as well.
Ricketts surrendered just one hit in her three innings before Michelle Gascoigne came in and through two hitless, shutout innings—she did allow a pair of walks—in relief.
OU's bigger test now comes against 21st-ranked foe Arkansas at 1 p.m. Saturday.
"We respect them tremendously," Gasso said. "We know that they've had success in the SEC, which is a very good conference. And they're very athletic. They swing the bat well. They pitch well, so it's gonna be a big challenge for us and we know that."
Marist drops into an elimination game with No. 3 Fordham at 3:30 p.m.