Senior Tyler Sheffner scored a pair of fourth-quarter rushing touchdowns Friday, the second with 7:42 left. A Peter Marquez conversion kick knotted the score at 28-28 and Katella missed a 45-yard field-goal attempt wide left on the final play of regulation.
Using the overtime format popularized by the college game, Katella opened overtime on the Mesa 25-yard line.
After three runs gained 12 yards, quarterback Roberto Resendez scrambled 13 yards around the right side for a touchdown. Resendez then booted the PAT.
Mesa needed five plays to answer with a touchdown of its own, with Sheffner bowling over the goal line on a six-yard swing pass from Nathan Alvis.
After a Katella called timeout, Mesa went for two. But Alvis was sacked to leave the visitors (0-3) one point short.
Things looked bleak for the Mustangs at halftime, after they managed just 13 yards of offense to the Knights' 262.
Katella's double-wing offense produced touchdowns on its first four possessions, though Costa Mesa senior DeSean Grayson answered the first score with a 90-yard kickoff return for a touchdown.
Costa Mesa scored on the opening possession of the second half, when Alvis hit Jordan Walden on a 16-yard touchdown pass to close the gap.
A high snap, one of four such miscues in the shotgun and punt formation (for losses of 60 yards), gave Katella (2-0) a safety that upped its lead to 28-14 with 3:55 left in the third quarter.
But a Costa Mesa defense led by Sheffner, Nick Cendoya, Nick Guzowski, Tyler Biggs and Ryan Barnett, among others, kept shutting the Katella offense down.
Costa Mesa had possession at its own 35 with 2:20 left in regulation. But, after a first down, a high snap lost 11 yards and stalled the drive that eventually ended in a punt.