AUSTIN, Texas (AP) - BYU had a chance to make a big statement. A week after a road win in the Southeastern Conference, the Cougars were dominating Texas in the Longhorns' backyard.
Up 13-3 at the start of the third quarter, they were well on their way to making the country take their newly independent program seriously this season.
But a quarterback change by Texas and a punishing Longhorns running game in the second half changed everything.
Backup quarterbacks Case McCoy and David Ash pumped new life into a struggling Texas offense and Cody Johnson scored a fourth-quarter touchdown as the No. 24 Longhorns rallied to beat BYU 17-16 Saturday night.
"Everybody was feeling it, everybody was feeling really confident," BYU quarterback Jake Heaps said. "It's tough to lose a game like this, especially when we let someone come back and beat us. It's uncharacteristic of our football team."
Heaps passed for 235 yards with one touchdown and two interceptions for the Cougars (1-1). Justin Sorensen kicked field goals of 30, 33 and 32 yards.
Convert a couple of those field goals into touchdowns and BYU likely wins, Heaps said.
"You can't do anything but just go, 'OK, next drive, next drive," Heaps said.
BYU had rallied from 13 points down a week earlier to beat Mississippi and was rolling to another big win.
But McCoy, the younger brother of former Texas quarterback Colt McCoy, and Ash started rotating snaps after ineffective starter Garrett Gilbert was pulled in the second quarter.
Ash's early runs helped set up Texas' first touchdown on a short run by Johnson. McCoy took most of the snaps on the drive to the winning touchdown, twice hitting Jaxon Shipley for big gains before Johnson scored again.
"It's just not us," BYU offensive tackle Matt Reynolds said. "Close games, that's where we're at our best and we weren't there tonight."
Texas' new quarterback duo may push Gilbert out of the starting role.
McCoy and Ash combined for 9-of-11 passing for 92 yards. Ash also ran for 36 yards.
"When I was named the backup, I knew that you're always one play away," McCoy said. "I felt our team rallied around me and David."
Gilbert won a four-way battle in training camp to keep the starting job after throwing 17 interceptions in Texas' 5-7 season in 2010. But he was just 2 of 8 for eight yards with two interceptions and was lustily booed by the home crowd before he was pulled.
After the second interception, Heaps drove BYU 97 yards on 13 plays for the only touchdown of the half, a 6-yard toss to Ross Apo for a 13-0 Cougars lead.
The McCoy-Ash rotation failed to pick up a first down on its first series. The Longhorns (2-0) finally scored after Heaps threw an interception on the BYU 29 and Justin Tucker kicked a short field goal to make it 13-3 at halftime.
Texas stuck with the backup QBs to start the third quarter and scored on its first possession.
The Longhorns drove 68 yards - all on the ground - to set up Johnson's 1-yard touchdown run that made it 13-10. D.J. Monroe provided the big play with a 29-yard run and the BYU defense, so stout up to that point, looked helpless against Texas' power and speed rushers.
BYU coach Bronco Mendenhall was impressed with Ash's running the option that started opening up the Texas offense.
"He played with a lot of heart, toughness, and I think it made a difference in helping them with time of possession," Mendenhall said.
BYU led 16-10 after Sorensen's third field goal, but the Cougars were clearly unsettled on both sides of the ball. The Cougars managed just one first down in the second half.
McCoy then led an 8-play scoring drive that started at the Texas 48, connecting twice with Shipley for big gains before Johnson scored on a 4-yard run up the middle that put Texas ahead for the first time with 8:46 to play.
The Longhorns put the game away with a trick play reverse pass from Shipley to David Ash that picked up a key third down with under 3 minutes to play.
"We played them well and we could have, quite frankly should have, walked away with a win," Heaps said.