Twice the Sooners got behind, and twice third baseman Garrett Carey put the Sooners back on top.
He did so for good the second time, bringing home right fielder Cody Reine to win it on his walk-off single in the bottom of the 10th.
"Luckily I got the game in my hands again at the end and was able to capitalize," Carey said.
But it didn't come without a struggle.
It was Carey who committed the error that allowed Missouri to notch things up in the ninth.
Carey botched a weakly hit ground ball down the third base line, allowing Missouri third baseman Conner Mach to race home with the Sooners just one out away from the victory.
The Tigers then took a 5-4 lead in the visiting half of the 10th, thanks to another Sooner error, a booted grounder by second baseman Jack Mayfield.
Shortstop Caleb Bushyhead, though, led off with a single, advanced to second on a sacrifice bunt and, after Missouri intentionally walked Reine, scored on designated hitter Evan Mistich's game-tying RBI double.
That set the stage for Carey's heroics.
"You know, I was pulling for him, I was pulling for him," said OU head coach Sunny Golloway. "And when he kept fouling balls off the other way, I knew he was getting some tough pitches, tough pitches. He's really good middle in, and they had to know that because that's the scouting report. Just he hit a mistake. The pitch was in, and he rapped around it and it was really big.
"So, I'm excited for him. After the ground ball, I'm excited for him."
The teams played just an inning-plus of scoreless ball before the extended lightning/inclement weather delay.
Shortly after that, Missouri took an early 3-0 lead through 3 1/2, as left fielder Dane Opel blasted a two-run shot to right in the second and designated hitter Scott Sommerfield added an RBI single in the fourth.
But it was OU's turn to buck the recent trend in this one after seizing an early lead in all three of their contests last weekend at Texas A&M and falling short in the late stretches.
"You tell me what speech you're going to give to this team after losing Friday night to Texas, Friday night extra innings to A&M [and again tonight]," Golloway said. "You know, to lose on Friday is one thing, 6-4 a solid game. But to lose extra innings, you know, and have to come back and rebound has been very difficult to do."
They wouldn't have to.
The Sooners battled back in their half of the fourth.
A Bushyhead walk and hit by pitch by center fielder Max White preceded Mistich's two-run ground rule double.
OU got back to work in the sixth when Lockwood laced a double down the left field line and Reine tied it up on his triple one batter later.
Carey then gave OU the lead on his RBI double before things got interesting late.
Pitcher Jordan John picked up the victory in relief, despite allowing a run in the top of the 10th, while Missouri reliever Jeff Emens was tagged with the loss after surrendering the tying and winning runs as part of his 1 2/3 innings pitched.
Four Sooners (Carey, Lockwood, Mistich and Reine) recorded two hits, and Bushyhead actually finished with three hits in five plate appearances.
Mistich actually led the way with three RBIs in helping prevent the Sooners (20-14, 5-8 Big 12) from dropping even further below .500 in conference play.
"This team's been challenged," Mistich said. "We've had a lot of ups and downs throughout this year, and I think it's gonna work well for us towards the end of the season. And I think just all these ups and downs, ups and downs, I think if we just keep on getting better like I think we are, I think it's gonna come out with some better results for us later in the season."
OU and Missouri will get back at it at 11 a.m. Saturday, weather permitting.