Goals from Ollie Pearce and Dan Thompson earned Bognor three vital points away to leaders Dulwich Hamlet in their push for the Ryman premier play-offs.
It completed an impressive league double over the south London side and cemented fourth spot for the Rocks, who still have games in hand over five of the other sides in the top seven.
The Rocks took a deserved lead on 15 minutes when Pearce slotted home from a low Kane Wills cross.
Bognor had the better of the chances and just before half-time, Pompey loanee Ashley Harris’ dipping free-kick was tipped just over the crossbar
Harris looked dangerous soon afer that, weaving his way in from the left – only this time to see his effort just fly past the post.
Dulwich took their time to get into the game, but did eventually create a few chances and Ellis Green had a shot from long distance go just over.
The home side appealed for a penalty when captain Kevin James felt he was upended in the Bognor box, but nothing was given.
Bognor had their own penalty appeal fall on deaf ears when Pearce appeared to be dragged down - once again, the referee didn’t signal to the spot.
Dulwich piled on the pressure towards the end of the half, forcing Rocks keeper Grant Smith to make a series of reflex saves to keep his side’s one-goal advantage.
The second half was an absorbing contest but Dulwich created few clear-cut chances as they fought to get back into it.
Bognor extended their lead with two minutes of the match remaining through Thompson,.
Another Wills cross caused all sorts of problems and Thompson jumped above the Dulwich defence to score
It was just reward for a half Bognor shaded.
Smith in the Rocks goal had little to do until the 81st minute, when he had to stay alert after a Jordan Clarke shot.
ROCKS: Smith, Hinshelwood, Crane, Tuck, Axten, Robson, Harris, Wills, Dodd, Pearce, Whyte. Subs: Chamberlain, Thompson, Hopkinson, Sackman, Wollers.
The Rocks are on the road again on Tuesday night when they visit Met Police.