Ryan Agnew - Derrick Tuskan
San Diego State quarterback Ryan Agnew (9) dropping back for a pass in the game against Sacramento State on Sept. 8. Photo by Derrick Tuskan/SDSU

It’s the second week in a row that San Diego State football will face a ranked opponent, but this week the Aztecs will have to do so without starting quarterback Christian Chapman.

Chapman was injured with 4:47 left in the second quarter in last week’s win against Sacramento State. He was hit below the waist by Hornets defensive end David Perales following an incomplete pass. The hit was unintentional but the damage was done.

The starter is sidelined for three to six weeks from an MCL sprain. That means Ryan Agnew will make his first collegiate start Saturday against No. 23 Arizona State. Agnew has already proven himself by leading the Aztecs to a fourth-quarter victory on a 13-play, 82-yard scoring drive against the Hornets last weekend.

This week, he’s hoping to repeat that same performance.

“There’s definitely challenges going into the first game,” Agnew said. “I just have to be as calm as I can and trust the guys around me. They did a great job when I came in last game. They trust me. All I can do is do my job, and trust that they’re going to do their job and we’re going to be OK.”

Even though it will be Agnew’s first career start, coach Rocky Long isn’t worried. Agnew was a starter in high school and knows the challenges and pressure quarterbacks face, he said.

“Nothing will frustrate him that doesn’t every other quarterback in the country,” Long said. “If you’re getting sacked or not having success, that would frustrate him, but that frustrate Christian (Chapman) and Arizona State’s quarterback (Manny Wilkins) too. It doesn’t make any difference. He’s prepared because he’s been here for four years.”

What has Long worried, though, is the fact that Arizona State knows all of SDSU’s secrets. Two of the Sun Devils assistant coaches, Danny Gonzales and Tony White, coached for SDSU last season.

“The biggest concern I have right now after listening to the radio coming in was that I heard the New York Jets had all the Detroit Lions signals and the score was 48-to-17,” he said. “Guess who is going to have all of our signals and all of our hand signals? Arizona State is going to have that. We’re not going to have theirs, but they’re going to have ours.

The Aztecs have a 10-1-1 series advantage over the Sun Devils, but Long admits Saturday’s game comes with a host of challenges.

“It’s an opportunity for us, but I’d say we are the big underdog,” he said.

Saturday’s game, which will air live on CBS Sports, is the second of a three-game homestand for the Aztecs. Kick off is at 7:35 p.m. at SDCCU Stadium.