Timing Guns : Long groomed as Westlake quarterback, Preston capitalizing on midseason promotion.

Buried inside the slick 140-page Westlake High football program is a 1990 photo of four grade-school ballboys wearing oversized Warrior jerseys. Squinting at the camera with unkempt hair hanging in his eyes is 11-year-old Casey Preston, who at that very moment knew precisely where he would be in five years.

Now a 6-foot junior quarterback, Preston leads upstart Westlake (7-4-1) into the Southern Section Division III semifinals against Newbury Park (12-0) at 7:30 Saturday night at Thousand Oaks High.

Preston has been groomed to be the Westlake quarterback since he and his father informed some long-forgotten youth coach of his bent when Casey was 7.

Casey worked on getting the wobbles out of his spirals playing catch with his brother, Todd, a quarterback who was Westlake’s most valuable player in 1989-90.

It was always Westlake. It was always quarterback. Even when Casey began to feel the pressure of being a passing Preston.

“I wanted to be like Todd when I was little,” Casey said. “It kind of bothers me now, having to live up to his expectations.”

However, the pressure this season had more to do with replacing another top player.

At halftime of Westlake’s Marmonte League game against Newbury Park six weeks ago, Preston was thrust into the lineup for the first time, replacing popular senior Steve Aylsworth, who moved to receiver.

Westlake lost, 18-7, but Preston led the team to its only touchdown. He has improved each game, culminating in a 281-yard passing performance in a quarterfinal upset of top-seeded Notre Dame.

“That was the best football game any quarterback at Westlake has ever had,” Coach Jim Benkert said. “I already knew he had the physical talent, but his maturation has been steady. He not only threw the ball well, but he changed plays at the line . . . to make it happen.”

In a matter of weeks, Preston has gone from frightened to putting a scare into opposing defenses.

“When I first went in for Steve, it totally surprised me,” Preston said. “I was nervous and I really just went through the motions trying not to embarrass myself. This time I’m a lot more prepared.”

Leadership has not been a problem, even though the guy Preston replaced is standing next to him in the huddle.

“Everybody respects Casey and I was actually kind of relieved when Coach Benkert made the change,” said Aylsworth, who passed for 876 yards and seven touchdowns.

As Preston has improved, so has Aylsworth as a receiver, making 29 receptions, including six for touchdowns. Aylsworth has 16 catches for 224 yards and four touchdowns in two playoff games.

“Steve is a good quarterback, but he’s a better receiver,” Victor said. “Casey is a good quarterback too, so it just made the team better.”

In five and a half games, Preston has completed 82 of 152 passes for 1,083 yards and eight touchdowns with six interceptions. In a first-round 35-14 upset of Bell Gardens, Preston threw for four touchdowns, and against Notre Dame he threw for two more, including a 92-yard hookup with Jason Victor.

His counterpart in the semifinal, Newbury Park junior Chris Czernek, is the state’s leading passer with 3,995 yards and 43 touchdowns. Preston, however, is more concerned with the Newbury Park defense.

“We have to get our running game going to open up the pass,” he said.

Win or lose, Preston will get a phone call Sunday morning from his brother. Todd finished his football eligibility at Cincinnati last year but still attends the school.

Todd has yet to see Casey play, although he will be home next week for winter break and will watch the final should Westlake defeat Newbury Park.

“Todd will be impressed with his brother,” Benkert said. “Todd was a great one at Westlake but Casey is making his own name now.”