DALLAS — Dillon Gabriel knew he couldn’t take a sack as the pocket collapsed around him in the closing seconds of his Red River rivalry debut, the kind of big game he went to Oklahoma to play.

Then he saw Nic Anderson in the back of the end zone.

“The rest is history,” Gabriel said.

Gabriel appeared to do a jump step and connected with Anderson for a 3-yard touchdown with 15 seconds left as 12th-ranked Oklahoma won a battle of unbeatens 34-30 over No. 3 Texas on Saturday in their last matchup at the State Fair of Texas as Big 12 members before moving to the Southeastern Conference.

“Just proud of everyone coming together, controlling the chaos,” said Gabriel, a Mililani graduate who set the Hawaii high school passing yardage record. “It’s something you dream of as a little kid.”

With the SEC commissioner in attendance, but not the Big 12’s, the Sooners (6-0, 3-0 Big 12) and Longhorns played a classic that must have made Greg Sankey thrilled with his new acquisitions.

Gabriel completed 23 of 38 passes for 285 yards and ran 14 times for 113 yards and a score. The left-handed quarterback, who wore a lei on the field after the game, had transferred from UCF before last season but missed the Sooners’ 49-0 loss to Texas last October because of a concussion the previous week.

“He’s the calmest guy I’ve ever been around at the quarterback position,” Sooners coach Brent Venables said. “He was fearless. I don’t put any limits on what Dillon can do. He’s playing as confident as anybody on our team right now.”

The Longhorns (5-1, 2-1) had erased a 10-point deficit and taken a 30-27 lead on Bert Auburn’s third field goal, a 45-yarder with 1:17 left. Oklahoma then went 75 yards in five plays, including Gabriel’s passes of 11 and 28 yards to Drake Stoops, the senior receiver and son of the former Sooners coach.

“We didn’t play our best football today. Our inability to corral the quarterback … hurt us, especially in the second half,” Texas coach Steve Sarkisian said. “The promising thing is we know we can play better than we did today. And we will.”

They could play the Sooners again, if both make it to the Big 12 championship game on Dec. 2.

Quinn Ewers was responsible for all three Texas turnovers, with two interceptions and a fumble, but completed 31 of 37 passes for 346 yards. His final throw from near midfield was knocked down near the goal line as time expired.

“Just didn’t start out how I wanted to. It’s always tough whenever you throw interceptions on the first two drives,” Ewers said. “I liked the way we bounced back.”

Jonathon Brooks, held out the end zone on three consecutive plays after Texas got to the 1 on its previous drive, tied the game at 27-27 on a 29-yard TD run with 6:10 left. Brooks finished with 129 yards rushing, his fourth consecutive 100-yard game.

The Longhorns had gone for it on fourth down, but Xavier Worthy was hit immediately short of the goal line after a quick pass from Ewers. Oklahoma then drove 72 yards before Zach Schmit’s 45-yard field goal attempt came up short.

For Sankey, it was his first trip to one of college football’s most storied rivalries. Mayfield, with Tampa Bay in its open date of this NFL season, and actor and Texas superfan Matthew McConaughey were also present.

Ewers, who had four TD passes in last year’s romp over the Sooners, threw his interceptions on the first two drives. But the game was tied 7-7 after a wild sequence that included those two picks and blocked punt recovered for a touchdown by Texas’ Malik Muhammad.