Estancia is 4-0 in the Orange Coast League, trying to win the school's first league title in girls' basketball since 2003.
But the Mustangs also come into Tuesday night's tilt with a 4-0 league record. As the teams end their first go-round through league play, first place is on the line.
Added incentive? Castellano said not really, because winning the bell game should be incentive enough.
"As a kid, it's the biggest thing in the world," Castellano said. "Nobody wants to lose that game. I think it's fun for the girls, fun for the city."
Costa Mesa, which last won league in 2008, held an 11-game winning streak over Estancia under former Coach Jim Weeks before the Eagles won in 2009. Now, Estancia has its own four-game winning streak in the rivalry.
The Eagles (14-6) and Mustangs (9-11) have established themselves as the best teams in the six-team league. Estancia is led by last year's Daily Pilot Dream Team Player of the Year, senior Kassie Stratton, a University of Colorado at Colorado Springs signee.
Stratton averages 14.6 points per game but the Eagles also get sizable contributions from up-and-coming freshman Celia Duran (9.8 points per game) and senior Yessenia Maldonado (9.7).
But Castellano also recognizes the job that second-year Coach Nichole Maddox is doing at Mesa. The Mustangs have been preaching defense all year long, and they are also coming together behind seniors Annie Strum (13.9 points and 8.6 rebounds per game) and Itzel Flores (6.7 points, 6.1 rebounds and 4.1 steals).
Sophomore guard Marilyn Armstrong, averaging 10.5 points per game, is another standout player Maddox has at her disposal.
"We have to use these games to our advantage to work toward that Estancia game," Sturm said after her team's 52-26 drubbing of Calvary Chapel on Tuesday.
The winner of Tuesday night's clash takes over outright first place, but you won't catch Castellano thinking too far ahead.
"We've still got five more games to go," he said.
Now he sounds like a coach again.