East, seeded No. 9 in the 16-team tournament, and No. 8 Henderson will meet again at J. Oscar Dicks Stadium, where on Friday the Warriors overcame a 20-7 deficit to beat the Cougars, 42-20, to clinch the National Conference championship.
Two other Class AAAA first-round contests will pit members of the same league against each other: No. 12 Ridley at No. 5 Garnet Valley (Central League) and No. 15 Pennsbury at No. 2 Abington (Suburban One League National Conference).
Ridley will get the chance to avenge a 21-19 home loss to Garnet Valley on Oct. 6; Pennsbury gets a second crack at beating Abington after bowing to the host Ghosts, 20-7, on Oct. 14.
At Sunday's district seeding meeting, a few coaches voiced their displeasure with playing a fellow league member in a playoff opener.
Trailing East by 13 at intermission, Henderson notched five unanswered touchdowns in the final 24 minutes to secure its first league title since 2007.
"The second half was a disaster for us," East coach Mike Matta said. "We haven't had a disaster like that in years."
Quarterback Jake Richard sparked the comeback with 246 rushing yards and three touchdowns. "He put the team on his back and carried it," Walsh said. "He made some incredible plays."
The other key contributors for a veer-option offense averaging 32.3 points per game are halfback Zack Jones, fullback Derek Matonti, and tight end T.J. White.
The Warriors' offensive line is made up of center Nick Gustaitis, guards Kevin Regan and Brian White, and tackles Max Perisse and Matt Eichman.
A defense yielding 13.6 points a game is headed by tackles Perisse and Tom Kolongowski, end Regan, linebackers T.J. White and Adam Weaver, free safety Jones, and cornerbacks Richard and Spencer Rymiszewski.
In the second quarter against East, Chris Mitten, a strong safety, had to be taken off the field by ambulance. "He's doing fine," Walsh said. "He had a little neck bruise."