Watch KXAN’s Roger Wallace and Chris Tavarez break down Texas’ loss in the Red River Showdown.

DALLAS, Texas (KXAN) — Texas Longhorns quarterback Casey Thompson injured his thumb while following through on a throw in the second quarter. It didn’t matter much during a dominant first half of football at the Cotton Bowl Saturday.

The Longhorns were excellent in every phase of the game during the first 30 minutes of its battle with Oklahoma. The offense was explosive, tallying 38 points. The defense forced two turnovers while special teams joined in with a blocked punt to send the burnt orange side of the Cotton Bowl into a frenzy.

Everything changed after halftime.

OU’s defense forced Texas into three-and-outs on three of its first four second-half series’. OU freshman quarterback Caleb Williams replaced Spencer Rattler and marched the Sooners up and down the field for 35 points.

Special teams even swung to the Sooners as Longhorns receiver Xavier Worthy fumbled a kickoff in the fourth quarter. On the next play, OU took its first lead of the game at 48-41.

The 2021 Red River Showdown will go down in the record books and Texas would rather forget the second half.

OU’s 55-48 come-from-behind win is the largest comeback in the history of the rivalry.

Thompson said after the game he did injure his hand, but was able to keep playing. Just think what he could’ve done at full health. Thompson tied the Red River Showdown record with five passing touchdowns.

Texas has to rebound quickly, facing an undefeated and motivated Oklahoma State next Saturday in Austin.