Hampered by poor shooting and struggling to score, the Sooners were reminiscent of head coach Jeff Capel's first team here as they dropped a 66-55 decision at Southern California.
Oklahoma shot just 35.6 percent (21-of-59) overall while falling to 5-2.
It was especially rough going in the first half when the Sooners had trouble making it from any spot on the floor.
Oklahoma was 7-of-28 from the field, 2-of-14 from 3-point range and even 2-of-7 at the free throw line.
Still, the Sooners managed to stay in the game with the 22nd-ranked Trojans, who improved to 6-1.
Oklahoma led 13-12 with about eight minutes left in the first half, but USC's Davon Jefferson score eight straight points to spark a 10-1 Trojan run. Oklahoma never led again.
The Sooners trailed 29-18 at halftime, but played their best stretch to start the second half.
Austin Johnson scored seven of his 13 points during the first 7:35 of the half as OU pulled within 39-36. That's as close as the Sooners got.
Tony Crocker held Mayo to just four points in the game's first 31 minutes, but Mayo heated up to finish with 18 as the Trojans pulled away in the final minutes. Jefferson did most of the damage with 23 points.
Griffin was held to just four points and attempted only four field goals. Frontcourt mate Longar Longar scored only three points as the Sooners failed to utilize their size advantage.
Johnson was the only Sooner to score in double digits. Guard Omar Leary added nine and Godbold eight.
Oklahoma will play TCU at 7 p.m. Sunday in Ft. Worth, Texas.