Eric Gay, AP
Texas' David Ash (14) during the second half of an NCAA college football game against North Texas, Saturday, Aug. 30, 2014, in Austin, Texas. (AP Photo/Eric Gay)

PROVO — BYU will be facing a short-handed Texas team when it invades Darrell K. Royal-Texas Memorial Stadium.

First-year Longhorn coach Charlie Strong announced Monday that quarterback David Ash (concussion), center Dominic Espinosa (leg injury) and wide receiver Daje Johnson (academic issues) won’t play against the Cougars Saturday (5:30 p.m., MDT, Fox Sports 1).

According to Strong, Ash seemed fine after his team’s 38-7 win over North Texas last Saturday, but later that night complained of a headache and dizziness and met with trainers. Strong said it is believed that Ash was injured in the first quarter while attempting to recover a botched snap.

"It's not like it's the end of the world,” Strong said Monday of the loss of Ash. “We know we've got to go play a game, and that's what we're going to go do. … Not one player would ever change the dynamics of this football team."

Ash suffered a concussion in the fourth quarter last year during BYU’s 40-21 victory over Texas in Provo and missed 10 games in 2013.

Monday’s news required the Cougar defense to alter its preparations. Ash’s replacement is sophomore Tyrone Swoopes, who will make his first collegiate start.

“I thought Ash was a really good player. But it is the University of Texas and they have a really good backup,” said BYU coach Bronco Mendenhall. “We’ve actually seen (Swoopes’) film through the spring game. He played some in the bowl game. He’s fast, athletic and big, just what you’d expect at a really quality program. The game plan might change a hair, but it’s week two. How much you deviate from what you’re going to do the rest of the year will be interesting.”

Swoopes played sparingly last season, passing for 26 yards and rushing for 79 yards and a touchdown in six appearances. He got into Saturday’s game for two kneel-down plays. His backup is freshman Jerrod Heard.

“Tyrone can handle it,” Strong said. “I’m not concerned about that. The team will rally around him.”

What are the differences between Ash and Swoopes?

“Ash seemed to be a little more mobile. (Swoopes) is more of a pocket passer," said Cougar defensive lineman Remington Peck. "So that will be a little different but I don’t think they’ll change much of their offense for it.”

Texas running back Malcolm Brown said he and his teammates have confidence in Swoopes.

“Tyrone is going to be fine. I know he will. Once Tyrone gets a couple completions in, he'll start getting a little rhythm and he'll be fine,” Brown said. “He's a guy that I've seen work since he's been here. I know as a backup, you always feel like you have to go above and beyond, but that's not the case at all. Just have to be consistent.”

Espinosa, a fifth-year center who made his 40th career start Saturday, suffered his injury against North Texas. Espinosa’s backup, Jake Raulerson, had some struggles Saturday, including a fumbled snap exchange with Ash.

Mendenhall said the loss of Espinosa might be more impactful than the loss of Ash.

“Probably more so than the quarterback in terms of the quarterback-center exchange, making line protection calls, being able to handle that. If the roles were flipped, that would probably be a bigger issue,” the coach said.

With Ash sidelined, Strong said his team will rely even more heavily on other players, particularly the running backs — Brown and Johnathan Gray.

"You have players and that's why you have scholarships,” he said. “It's not all about one person. Other players have got to step up, other players have got to play. It can happen to any team at any second."

The Longhorns will also have to rely on their defense to step up. Last year, Texas surrendered 550 rushing yards to BYU, including 259 to quarterback Taysom Hill.

“It's all about execution on the defensive side,” said Longhorn safety Mykkele Thompson. “We didn't execute last year and we gave up big plays. That's what we are trying to eliminate this year. Just execute good plays.”