And five runs would be more than enough for the Tigers, who got a magnificent performance from No. 1 starter Max Scherzer.
Scherzer, who could potentially be a first round pick in the upcoming Major League Draft, shut the Sooners out threw seven innings with a fastball that reached 98 miles per hour several times to go with a baffling changeup. He gave up just four hits while striking out five.
Oklahoma's biggest threat was in the third, when Jackson Williams and Freddy Rodriguez put together back-to-back hits with one out, but Scherzer responded by striking out Chuckie Caufield and Ryan Rholinger to end the inning.
In all, the Oklahoma pitchers gave up just eight hits, but three errors led to eight unearned Tiger runs.
Steven Guerra started for the Sooners and gave up six runs, only two earned, over five innings. Guerra's record dropped to 10-3 on the season, while Scherzer improved to 7-1.
Missouri scored four runs in the bottom of the seventh, which pushed the lead past 10 and put the game-ending run-rule into effect.
The Sooners, now 39-19, will play their third and final Big 12 tourney game against Oklahoma State at 5 p.m. Saturday. The Cowboys also come into the game 0-2 in Big 12 Tourney pool play after their loss to Kansas Friday night.
Senior Daniel McCutchen (7-7, 3.52) is set to start for the Sooners.
The winner of Saturday's Kansas-Missouri and Texas-Nebraska matchups will meet for the title on Sunday.
OU-Missouri Box Score
Sooners run-ruled by Missouri in game two
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