Editor's note: updated 11/27/11 at 10:45 p.m.

It only took them 11 games, but the Longhorns finally found a quarterback.

Garrett Gilbert started just two contests. David Ash lasted five games as the full-time quarterback before Case McCoy earned the start against the Aggies. The sophomore signal-caller made the most of the opportunity, helping Texas overcome a 13-0 first-half deficit and say goodbye to A&M in dramatic fashion. The Longhorns triumphed over the Aggies, 27-25, at Kyle Field on Thursday night in the final Lone Star Showdown before Texas A&M moves to the SEC next summer.

With Texas trailing 25-24 after a 16-yard touchdown pass from Ryan Tannehill to Jeff Fuller, McCoy marched the offense 48 yards downfield into Aggie territory. He completed four of five passes on the drive, with Texas A&M getting flagged for a personal foul on the only incompletion. But it was his 25-yard run in the final minute that put the Longhorns in a position to win and cemented McCoy’s place atop the depth chart.

“Here’s where you come out,” head coach Mack Brown told McCoy before the final drive. “Here’s where you become the guy, and here’s where you take us down and win the game. Every quarterback has a signature moment. This is going to be yours.”

McCoy’s scamper and Cody Johnson’s short run to put the ball between the hashes left Justin Tucker with a 40-yard field goal attempt. A game-winning kick by Kris Stockton in the final minute of the fourth quarter gave Texas a win in Brown’s first meeting with Texas A&M in 1998. Tucker, whose 40-yard boot did the same for Brown in his last scheduled meeting with the Aggies, said the clutch situation is one he’s practiced with his father since his high school days.

“My dad and I would set up a ball, and he would tell me a game situation,” Tucker said. “He said, ‘Alright, there’s three seconds left on the clock. There’s no timeouts. It’s going to be a 40-yard kick to beat A&M, 25-24 is the score. What are you going to do?’ And I would knock it down every time.”

The offense provided the late-game heroics, but the Longhorn defense turned in yet another fantastic performance. After allowing just 17 points apiece in the last two contests, both losses, they took matters into their own hands. Texas forced four turnovers, including three interceptions, one of which was returned 56 yards for a touchdown by sophomore Carrington Byndom in the third quarter. But the defense’s biggest play might have been denying Texas A&M a 2-point conversion following its final go-ahead score.

“We’ve got one of the best defenses in the country,” Brown said. “I really thought when they didn’t make the 2-point play, that we would win the game on a field goal.”

Case McCoy started for the first time since the Red River Rivalry, and with Jaxon Shipley back in the lineup after missing three games with a knee injury, the Texas offense seemed poised for a productive night. But the Longhorns were anemic in the early stages of the game, punting on their first six possessions. Even when the Texas offense produced points, it was unimpressive. The four scoring drives covered just 41, 3, 24 and 48 yards. But McCoy made the plays down the stretch that he needed to, likely cementing himself as the Longhorns’ full-time starting quarterback.

“We didn’t play good at all in the first half or most of the game,” McCoy said. “I don’t want this rivalry to be over, but if it had to end, I’m glad we went out on top.”

Texas didn’t need a prolific offense to take down Texas A&M thanks to its ball-hawking defense and solid special teams. The Longhorns turned a muffed punt into its first points as Shipley took a lateral from McCoy and heaved a 41-yard touchdown pass, his second of the year, to a wide open Blaine Irby in the second quarter. Quandre Diggs’ 81-yard punt return allowed Tucker to hit his first field goal and give Texas its first lead, 17-16, in the third quarter.

“Growing up watching these games, you just know how special these games are,” Diggs said. “When you come out and get the last win in this rivalry, it’s very special. It’s something you can tell your great-grandkids.”

Printed on Monday, November 28, 2011: McCoy makes case to be starting QB