CeeDee Lamb caught a 10-yard touchdown pass from Kyler Murray on Oklahoma's first possession of overtime and the fifth-ranked Sooners held off Army 28-21 Saturday in Norman.
Parnell Motley intercepted a fourth-down pass on Army's OT possession to seal the win.
The Sooners had a chance to win at the end of regulation, but Austin Seibert missed a 33-yard field goal to send the game to overtime.
Army (2-2) ran the ball 78 times for 339 yards.
Kenneth Murray had a school-record 28 tackles for Oklahoma.
OU (4-0) hosts Baylor at 2:30 p.m. Saturday.