Bognor lost to Lewes for the third time this season after conceding two goals in the first six minutes of the second half.
Terry Dodd’s goal gave them hope and Dodd and Jason Prior both had chances to claim a point, but it was the Rooks who went home with the Sussex spoils thanks to Elliott Romaine’s double.
It killed off Bognor’s play-off hopes once and for all, while going a long way to ensuring Lewes will stay up.
The Rocks went into the game knowing a defeat at Enfield on Saturday had left the Ryman premier play-offs virtually out of reach. Nevertheless, a Sussex derby is normally incentive enough to raise a team’s game - especially with Lewes having beaten Jamie Howell’s men twice at the Dripping Pan this season.
There were no surprises in the line-up, with Dodd again partnering Jason Prior up front and Jack Maloney and Stuart Green tasked with providing the service.
The two loan recruits from the Pompey Academy, Chad Field and Snorre Nilsen, were also in the starting XI.
Lewes had three ex-Rocks in their 16 - winger Arron Hopkinson and centre-half Chris Breach started and full-back Alex Malins was on the bench.
The Rocks almost had an opening in the first minute when Nilsen’s long ball found Maloney’s run down the left, but his attempt at a one-two with Dodd didn’t quite come off.
Lewes broke from that early scare and a long throw ended in Jack Rowe-Hurst rifling a shot only just high and wide in a lively start.
Three minutes in the Rocks had the ball in the net as Green pounced on the rebound from a Rikki Banks save but he was offside.
Lewes went close from an inswinging free-kick by Matt Crabb at the other end but the flag was up. Then Chris Winterton spilled a Hopkinson cross and a defender had to clear the follow-up shot for a corner.
Lewes, still in need of points to stave off relegation, were the brighter of the two sides in the opening ten minutes.
Bognor were forced into an early change when Maloney pulled up with an apparent hamstring injury. Harry Wedlake replaced him.
Worringly, Doug Tuck looked like he’d suffered a similar problem although was happy to try to run it off. He soon succumbed though and Dan Sackman came on for him.
The Rocks won a corner down the right and Prior’s free header from ten yards was cleared off the line.
Then it was Lewes’ turn to have a player in the wars as Breach went down with a cut to the head. He was bandaged up and led away for further treatment. Luke Blewdon came on in his place.
The Rocks had reshuffled, moving Craig Robson into Tuck’s role in midfield with Sackman slotting into the defence and Wedlake playing wide on the left.
Nilsen was fortunate to escape without a booking when he brought down Elliott Romaine just on halfway.
Matt Crabb just failed to clear the clubhouse roof with a wild shot from 25 yards.
A Jake Thomson corner was flicked on at the near post and Prior couldn’t quite get enough on it to force it in.
Lewes centre-half Gary Elphick was next in the wars, suffering a thigh injury in a goalmouth scramble. But unlike so many others, he was able to continue after treatment.
Prior and Dodd each found space for shots inside the box around the half-hour mark but neither was anything but comfortble for Banks.
Bognor were close to the opener on 38 minutes when Green raced on a long ball over the top and smashed in a low ball that was just too far in front of Dodd.
The Rocks missed a sitter three minutes before the break but in truth neither side was playing particularly fluent football.
During five minutes added on at the end of the first half, the Rocks had a shout for a penalty turned down and then Lewes broke to the other end and Hopkinson drew a foul from Robson just outside the box.
It took just three minutes of the second half for the Rooks to take the lead, Romaine glancing in a header after Winterton failed to gather a high cross under pressure and the loose ball was swiftly put back into the six-yard box.
Three minutes later Romaine did it again, converting from close range as the shellshocked Rocks defence failed to deal with a low ball across the box.
Prior almost pulled one back in a scramble close to goal on 57 minutes but Lewes hoofed it clear.
The Rocks made their final change a minute later with sub Wedlake replaced by Callum Overton.
Another chance went begging on the hour when Robson met a corner unchallenged but couldn’t convert it.
The Rocks pulled it back to 2-1 on 62 minutes. Sub Overton ran at the Rooks defence and released Green on the right. His low ball across the six-yard box was bundled in at the far post by Dodd.
Lewes made another change, Nicky Wheeler replacing Rowe-Hurst.
Thomson tried to level the score with a Charlie Adam-style long, long-ranger but it was never likely to come off.
The Rocks’ goal had added an extra intensity to the game with the hosts now believing they could salvage a point and Lewes desperate to hold on to the lead.
Dodd was close to a second on 69 minutes, volleying narrowly wide after Prior flicked on Thomson’s long pass to him in the area.
The Rooks showed they were still a threat themselves as Wheeler whizzd a shot over from 25 yards.
Dodd was taking the fight to Lewes and had the keeper needing two attempts to gather his low, long-range drive.
Dodd looked certain to equalise on 74 minutes when Green’s hooked pass put him in on goal. But he somehow shot wide when it looked easier to find the target.
It was all Bognor but their goal touch was deserting them - Crane the next to spurn a good chance, blasting over from 12 yards after good work from Green down the right.
It was the most open game you could wish to see now and Hopkinson skied a close-range chance after Wheeler’s accurate cross from the left.
The Rocks continued to go all-out for the equaliser but too often were let down by slack passing.
Prior missed the best chance of all to save a point in the 88th minute when his penalty - which he won himself for a quick turn in the box that saw him floored - was saved by Banks.
Hopkinson was replaced by Dan Huet in the final minute of the 90.
Prior so nearly made up for his spot-kick miss when he struck the post with a free-kick from the D. No-one could get on the end of the rebound and that was their final chance of salvaging a point.
The result left Bognor 12th in the table, eight points behind fifth-placed Grays.
Next for the Rocks is a home game against Leiston on Saturday.
Rocks: Winterton, Nilsen, Crane, Tuck, Field, Robson, Green, Thomson, Prior, Dodd, Maloney. Subs: Sackman, Wollers, Overton, Wedlake, Lawson.
Lewes: Banks, S Crabb, Badger, Breach, Elphick, Rowe, Rowe-Hurst, M Crabb, Romaine, Conlon, Hopkinson. Subs: Malins, Wheeler, Huet, Blewdon, Taylor.
Ref: Aaron Moody (Eastleigh)