Two goals by Matt Tubbs set Havant up to make it a miserable start to 2018 for the Rocks.
Sub James Hayter got the other as Bognor paid the price for having Ben Swallow sent off in the first half in a game in which the referee never seemed to have control. It leaves the Rocks still looking for their first home win since August - and they have yet another defensive injury worry after Chad Field went home on crutches after hobbling off with a leg injury that left him unable to walk unaided.
Bognor bosses said afterwards they would consider an appeal over Swallow's red card for a tackle on Tubbs - which they said looked a very harsh decision - and were fuming that an elbow by Brian Stock on Calvin Davies did not result in a sending-off for the Havant player.
It was a second meeting in seven days for the National League South near-neighbours, the first having ended in a 0-0 draw at Westleigh Park on Boxing Day. Bognor's starting line-up was the one that finished the game at Havant, with Keaton Wood now joining Corey Heath, Ollie Pearce and James Crane on the injured list. Havant were forced into changes from the last game because of injury and suspension but again had the familiar duo of Jason Prior and Matt Tubbs up front.
The first opening fell to Harvey Whyte in the fifth minute but he directed his free header straight at keeper Ryan Young after a nice exchange down the right between Davies and Swallow. Immediately the Hawks replied with a half-chance for Tubbs, whose shot from 18 yards was blocked. Ed Harris found the ball at his feet from a Havant corner but took too long and it was cleared for another corner.
Havant spurned a good opportunity on ten minutes when Andreas Robinson curled a 20-yard free kick into the wall and Wes Fogden fired the rebound wide. Bognor enjoyed a nice spell of pressure just before the quarter-hour mark that ended with Jimmy Muitt's pulled-back cross from the byline being headed off target by Field.
Rocks stopper Dan Lincoln was sharply out to beat away a Brad Tarbuck chance from close range on 18 minutes. Then he surpassed that with a flying one-handed save to keep out Ryan Woodford's header from the resulting corner. Tubbs fired Havant ahead on 19 minutes, lashing the ball in from close in after Lincoln had made a third great save in a couple of minutes by keeping out Jason Prior's header.
There was a huge setback for the Rocks on 24 minutes when Swallow was shown a straight red card for a tackle on Tubbs that left the striker needing treatment. The punishment looked harsh after both players went into the challenge fully committed. For a while Havant took advantage of being a man up with some possession football and the Rocks couldn't get the ball.
When they did get hold of it they won a corner which was cleared only for Whyte to swing a cross to the far post where Kristian Campbell made contact but couldn't keep the ball down. Muitt drew a foul from a Havant defender 25 yards out that had the crowd wondering why the visitors were not seeing any cards. He took the free-kick himself and curled it towards Sami El-Abd, who just failed to bundle it in at the far post.
Suddenly Bognor's tails were up and Whyte fizzed a grass-cutter just wide of Young's right-hand post. That was saved for a corner, from which Doug Tuck rifled a shot not too far wide. HT 0-1
Dan Beck replaced Tommy Block for the second half, his years of experience perhaps needed as Bognor sought to get back into a man down. In a fairly flat start to the season, Whyte was booked for an innocuous-looking challenge. Stock replaced Charley Tuttle in Havant's first change on 56 minutes.
Field and Jordan Rose were injured when both went full-tilt into a challenge for a loose ball on the touchline. Rose was okay to continue but Field, despite trying to run off his injury, had to give in to it and was replaced by Joe Lea.
Fogden robbed Davies in the box and forced Lincoln into another fine save - then a cross from the Havant right skimmed off the top of the Rocks bar. Lincoln was proving Bognor's MoM and made another great stop to claw away Tubbs' bid to lift the ball over him in a one-on-one. The corner fell to Rose, but he curled his shot straight at the Bognor hero of the hour.
Lea fired a 20-yard shot into Young's side netting in the 70th minute. Then Prior was booked for a late tackle on Campbell. Lewis was replaced by James Hayter for the Hawks' second change. Within minutes he had doubled Havant's lead, touching in a free-kick at the far post after Lee had been harshly judged to have brought down a Havant attacker a couple of yards outside the box down the Havant left.
All hell broke loose with 12 minutes left as Hawks sub Stock left Davies in a heap during a Rocks attack. With the home fans baying for a red card, ref James Durkin showed him yellow - and also booked Lincoln, who had come halfway up the pitch to see if Davies was okay. As the game reached a bad-tempered end, Muitt was booked for halting a Havant player in full flight.
With six minutes left Tubbs made absolutely sure there was to be no Rocks comeback when he slid in a Tarbuck cross from a couple of yards out. Campbell was replaced by Tommy Scutt in Bognor's final change, while Havant brought on Lee Molyneux for Rose. Tubbs missed a decent chance for his hat-trick when he pulled a shot across goal and wide when put through on Lincoln.
To their credit, Bognor kept on battling and Muitt's surge down the left ended in a ball into Tuck that Young did well to palm away. But it was a fruitless afternoon at the Lane for the Rocks - who have not won at home in the league since August 15. They go to Whitehawk, surprise winners at Eastbourne today, on Saturday desperately needing a win.
Rocks: Lincoln, Davies, Campbell, Tuck, El-Abd, Field, Whyte, Block, Muitt, Sekajja, Swallow. Subs - Beck, Lea, Scutt, Johnson, Boughton.
Havant - Young, Robinson, Rose, Tuttle, Woodford, Harris, Fogden, Lewis, Prior, Tubbs, Tarbuck. Subs- Stick, Walker-Harris, Molyneux, Hayter, Ridge.
Ref: James Durkin (Portland).
Get all the Rocks action and reaction in the Observer on Thursday