Westlake High's defense produced four turnovers and limited defending champion Arroyo Grande to 190 total yards in a 24-7 victory Saturday night in a Southern Section Division IV semifinal at Arroyo Grande.
Westlake (12-1) will play for its first championship since the school opened in 1978. The Warriors will meet San Luis Obispo on Friday night at Cal Poly San Luis Obispo.
Take away a 72-yard touchdown run in the second quarter by Chris Janowicz, and Arroyo Grande (10-2) would have been shut out on its own field.
Westlake linebacker Ben Lorier made three tackles for losses and recovered a fumble.
Westlake's offense came through with two decisive drives in the third quarter to turn the game into a rout.
With Westlake holding a 10-7 halftime lead, quarterback Zac Wasserman led the Warriors on a 55-yard drive, twice picking up first downs on third-down passes. Julian Lambert reached the end zone with a 16-yard touchdown run for a 17-7 lead.
Wasserman passed 30 yards to Michael Brignac for a touchdown with 1:02 left in the third quarter. Wasserman finished 16 of 29 for 173 yards and two touchdowns. Lambert rushed for 90 yards in 20 carries, including 81 yards in the second half.