OU knocked off Appalachian State 5-2 in the nightcap after winning 14-6 earlier in the day and rode through the loser's bracket to advance for a date with the South Carolina Gamecocks in Columbia starting next Saturday.
And it sets up an intriguing battle between the team that last beat South Carolina in the postseason and the Gamecocks, who are riding a 19-game NCAA Tournament streak.
The Sooners were able to get through on this night and win four games in two days in large part because of pitching in the second contest.
Drew Harrison, who got the ball in game two, had only made five appearances all season and put together six solid innings, allowing just two earned runs on three hits and three walks.
He struck out four.
Meanwhile, the offense again provided all that was necessary.
Second baseman Jack Mayfield followed up with a two-run double just off the outstretched arms of ASU's Brandon Burris.
It stayed 3-1 until the fourth when Mayfield recorded his third RBI of the game on a sacrifice fly.
ASU cut it to 4-2 in the top of the sixth courtesy of a triple and sacrifice fly, but OU got right back to work.
It got that run back on an RBI single into right center off the bat of catcher Tanner Toal.
The Sooners would need no more with the solid pitching.
With the win, Harrison moved to 1-0 on the year, while ASU starter Jeffrey Springs fell to 2-1.
Bushyhead and Oberste each ended with two hits, while Mayfield had the three RBI.
For the Mountaineers, designated hitter Daniel Kassouf was 1-for-2 with a walk and two RBI.
Now, as previously mentioned, it's on to Columbia, S.C., for the Sooners, where they must win a best-of-three if they hope to get back to Omaha for the second time in three years.
That series will start at 6 p.m. Saturday, with games to follow at 7 p.m. Sunday and 7 p.m. Monday if necessary.