Shane Austin has had to do much of his learning by watching.

Among the most vital lessons — stay ready.

Austin entered Hawaii’s season opener against USC listed third among the Warriors’ quarterbacks. But it didn’t take long for Hawaii’s depth at the position to be tested.

The Warriors ran three quarterbacks onto the field in the 49-36 shootout loss to the Trojans, again throwing a position rarely blessed with stability into flux.

"You always have to keep your mind right. You always have to know that shot could come at any time," Austin said after throwing two touchdown passes in an unexpected relief appearance.

Incumbent starter Bryant Moniz left the game after being leveled at the end of a third-quarter scramble.

UH head coach Greg McMackin stopped short of saying Moniz had a concussion, but "I didn’t want to take any chances" by putting him back in.

Brent Rausch made a brief appearance before taking a heavy shot himself and the UH coaches elected to give Austin a look in the fourth quarter.

The junior responded by completing six of nine passes for 141 yards and two scores to Kealoha Pilares to keep the Warriors within hailing distance of the 14th-ranked Trojans late in the game.

"Shane came in and did a nice job, Brent made some good throws," UH offensive coordinator Nick Rolovich said. "They got a lot of reps in spring in camp and I think they’re all dialed in.

"We’ll have to see how Mo is and go from there."

The trio combined to pass for 459 yards with no interceptions as three UH receivers — Pilares, Greg Salas and Royce Pollard — hit triple digits in yardage.

Moniz was 18-for-36 for 269 yards and a touchdown when he was hammered by linebacker Michael Morgan on a scramble with 2:35 left in the third quarter. McMackin said he complained to the officials after it appeared Moniz had taken a shot to the head.

That brought Rausch in for his first game action since mopping up in a win over Idaho on Nov. 22, 2008.

Rausch finished the drive by handing the ball to Alex Green for a touchdown, then completed his first three throws for 49 yards. But he took a big hit on a deep pass and his next drive ended with two sizable losses.

Enter Austin.

The third-stringer — last seen in UH’s overtime win at San Jose State last November — had been limited to mental reps since the top two tiers were settled early in fall camp. But he hit three of his first four throws, ending his first drive by finding Pilares across the middle for a 65-yard touchdown, cutting the USC lead to 42-30 with 6:48 left.

After another USC touchdown, the duo hooked up again on a 30-yard touchdown to cap the scoring.

"The receivers did a great job of getting open and our O-line, man, they played a hell of a game," Austin said. "I had a lot of time in the pocket."

Austin’s mother, Cathy, had been in town for all of camp and his father, Dave, flew in Wednesday night for the game.

"He’s stronger than I’ve ever seen him," Dave Austin said. "He said through adversity you learn and grow. I’m so proud of him. He was so composed and he was so ready."