Oklahoma freshman quarterback Spencer Rattler was briefly replaced by sophomore Tanner Mordecai during the second quarter of Saturday's Red River Showdown against Texas.

Eric Bailey of the Tulsa World reported that Rattler suffered a biceps injury, but Oklahoma head coach Lincoln Riley later said there was no injury concern, meaning Rattler was temporarily benched, per Bryan Fischer of Athlon Sports.

"They had been looking at his arm," Fox Sports' Jenny Taft said during the broadcast, per Nick Kosko of 247Sports. "That was so brief, and that was a while ago. He's been on the sideline involved. He has his helmet in hand. I think this was a wake-up call from Lincoln Riley."

Rattler left the game after his second turnover while the Sooners were leading 10-3. He was 8-of-13 for 74 yards with one touchdown, an interception and a lost fumble. He returned for Oklahoma's first drive of the third quarter.

Rattler won the starting job entering the season and had big shoes to fill, as Oklahoma's quarterbacks in the previous three seasons were Baker Mayfield, Kyler Murray and Jalen Hurts.

Things looked good initially, as Rattler threw for 290 yards and four touchdowns with zero interceptions in a season-opening win over Missouri State, but he was in for a rude awakening over the next two weeks.

Oklahoma was upset by Kansas State when Rattler threw for 387 yards and four touchdowns but also three interceptions, two of which played significant roles in the loss.

Last week, the Sooners were upset again, losing 37-30 at Iowa State. Rattler threw for 300 yards and two touchdowns with one pick.

Mordecai has some game experience. He attempted four passes in 2018 and went 16-of-26 for 207 yards with two touchdowns and zero interceptions last season.

With Oklahoma leading Missouri State 41-0 at halftime, Mordecai relieved Rattler and completed 14 of his 17 passes for 157 yards and one touchdown with one interception.

On Saturday, Mordecai went 5-of-7 for 52 yards with zero touchdowns and zero interceptions during the first half.

At halftime, the 1-2 Sooners and 2-1 Longhorns were tied at 17.