A late-arriving offense put TCU in a hole against No. 11 Oklahoma and the Horned Frogs weren't quite able to pull themselves out.
Trailing by 13 at halftime, TCU twice pulled within three points but Oklahoma used a late 76-yard touchdown run by Brennan Clay to hold off the Horned Frogs 20-17.
TCU (2-3, 0-2 Big 12) already is two games back in the conference race and a lack of offense is a prime reason why. The Horned Frogs didn't cross midfield in the first half, didn't record a first down until the 8:34 mark of the third quarter and finished with just 210 yards of offense - most of that in the final 24 minutes.
The Horned Frogs managed only 44 yards rushing.
"We have to find a way to win a game," TCU coach Gary Patterson said. "Give Oklahoma a lot of credit first half. No first downs. Physically outmatched us in the first half. In the second half, we had to find a way to win and we put ourselves in position. All three losses that we've had, we've been in position to win ball games.
"At some point in time you have to create luck. We have to execute. You can't go down and score as much as we did in an eight-minute period and do nothing the other 52 minutes."
After limiting Oklahoma to eight plays and four yards of offense in the third quarter, TCU pulled within 13-10 on a 2-yard touchdown run by Trevone Boykin. The Horned Frogs had two chances after that to take the lead but punted both times.
Oklahoma (5-0, 2-0) took over at its own 18 after the second punt. Clay carried for a 6-yard gain, then broke into the open and outran everyone for his career-long 76-yard touchdown run with 4:37 left. Clay finished with 111 yards on nine carries.
TCU quickly answered, as a 45-yard pass from Boykin to David Porter and a 21-yard screen pass from Boykin to B.J. Catalon led to an 8-yard touchdown scramble by Boykin with 2:26 left. But the Horned Frogs' deep kickoff went out of bounds and Oklahoma quarterback Blake Bell ran out the clock, running for a pair of first downs.
"We missed four tackles," Patterson said. "We even went back to last year. Their first third-and-1, they had not run their big set. We actually prepared for it on Thursday because I really felt just listening they were going to try something different. They came out and that's what they ran. And we didn't move our linebackers over like we were supposed to. At some point in time you have to be able to execute the game plan."
Oklahoma opened the game with seven straight defensive 3-and-outs, after finishing a 35-21 win at Notre Dame last Saturday with three. The 10 straight 3-and-outs was the longest such streak recorded by the Sooners since at least the 2003 season. The Sooners entered the game ranked fifth in the Football Bowl Subdivision in scoring defense.
The Sooners have won their last three games against TCU after the Horned Frogs posted a stunning 17-10 win in Norman in 2005.
TCU had entered the game having won 16 of its last 18 conference road contests.
The Horned Frogs didn't cross midfield in the first half and didn't record a first down until the 8:34 mark of the third quarter.
"I don't think that's ever happened, any one that I've been a part of," Oklahoma coach Bob Stoops said of his defense's first-half outing. "They played sensational. The guys were really aggressive, fast, played the run, played the pass really well. Otherwise, the way we were struggling offensively, if we weren't playing that strong defense, it would have been tough to win."
TCU did manage a 25-yard field goal by Jaden Oberkrom on that third-quarter series, which lasted for 12 plays and 7:17. That seemed to energize the Horned Frogs, which recovered a subsequent onside kick and drove 35 yards for a touchdown, with Boykin scoring on a 2-yard run to pull the Horned Frogs within 13-10.
The Sooners didn't record a first down in the second half until the 10:54 mark of the fourth quarter, after their defense had stopped TCU in Oklahoma territory. The Sooners, who had averaged 256.8 yards rushing per game during a 4-0 start, had 203 yards against TCU.