Closer Ryan Duke and the Sooners were just one out away from advancing to the winner's bracket of the Fort Worth Regional, but that's when things quickly changed.
DBU left fielder Austin Elkins ripped a game-tying single through the right side, plating first baseman Ryan Behmanesh, who reached on an infield single off pitcher Dillon Overton to start the inning.
That forced extras, and the Patriots wasted no time scoring again, this time off Sooner reliever Jordan John.
Pinch hitter Chris Haney, who closed the game in the bottom half, led off the top of the 10th with a bunt single.
After OU kept the runner at first on a 1-6 fielder's choice, Patriots' center fielder Landon Anderson singled to right, and right fielder Jason Krizan brought home the go-ahead and eventually winning run in second baseman Tyler Robbins on an infield single.
The Sooners threatened with a runner on second in their last at-bat, but back-to-back strikeouts prevented them from extending it.
DBU struck first when Anderson and Krizan recorded consecutive doubles to go up 1-0 in the first.
It took OU until the fifth to strike back, but it did.
Then, in the bottom of the seventh, catcher Tyler Ogle gave the Sooners their first lead of the game when he shot a single into right field, plating Ellis for the second time in the ball game.
Overton came on in relief of starter Michael Rocha in the eighth and stranded a Patriots runner at first by getting Krizan to strike out and shorstop Joel Hutter to pop out.
But OU couldn't add any insurance in the bottom of the eighth, setting the stage for DBU's heroics.
Rocha went 7 1/3 innings, allowing just one earned run, while striking out three and walking one in his second straight no decision and third consecutive appearance without a win.
DBU ace Brandon Williamson picked up the win, going nine innings and giving up two earned runs, while striking out seven and walking three.
OU's John was tagged with the loss, as he allowed an earned run on three hits in one-third of an inning.
The Sooners will face the loser of Oral Roberts-TCU at 2 p.m. Saturday.