Playing at their new temporary home of Oaklands Park, the Rocks went 2-0 down but goals from Nick Dembele and Seok-Jae Lee made it 2-2 and took it to a shootout.
The Rocks held their nerve to win that 8-7 and now go into the next round, a boost for manager Jamie Howell and his new assistant boss Paul Hinshelwood.
See pictures by Lyn Phillips and Trevor Staff on this page and those linked and get the Rocks latest in the Bognor Observer, out on Thursday,
5. Trevor Staff
Rocks v Sevenoaks, FA Trophy first qualifying round Photo: Lyn Phillips and Trevor Staff
6. Lyn Phillips
Rocks v Sevenoaks, FA Trophy first qualifying round Photo: Lyn Phillips and Trevor Staff
7. Lyn Phillips
Rocks v Sevenoaks, FA Trophy first qualifying round Photo: Lyn Phillips and Trevor Staff
8. Lyn Phillips
Rocks v Sevenoaks, FA Trophy first qualifying round Photo: Lyn Phillips and Trevor Staff