A last-gasp penalty cost Bury St Edmunds ground in the title race as they slipped to third, seven points behind London Irish Wild Geese in National Three London and South East.
After a promising first half where Bury ran in three tries to lead hosts Chichester 17-8 at the interval, a poor second-half performance saw Bury only manage to claim a losing bonus point when Dan Gray struck a penalty in the dying moments as Chichester won 23-20.
A sickness bug, injury and unavailability saw some key changes to the Bury line-up, but the 18 players on show were more than capable of the victory.
The early stages saw Bury on the front foot and after six minutes they took the lead.
A driving maul earned the visitors a penalty, which they kicked to the Chichester 22-metre line.
The ball went off the top of the lineout and was transferred down the line for Tim Mann to brush aside two ineffective tackles for a try by the side of the posts, but Freddie Henley-Hunter inexplicably missed the conversion.
Slowly but surely, the hosts eased their way into the game and, when James Solomon got isolated fielding a long kick, the Bury defence were then guilty of crossing as they tried to clear their lines and Gray slotted an easy penalty to reduce the gap to two points.
Boosted by the score, it was Chichester’s turn to dominate and Bury were clearly rattled.
Indiscipline began to creep in and a superb driving maul of nearly 30 metres was only ended with a penalty and the inevitable yellow card to Sam Bixby for stopping the maul illegally.
The Sussex side catch and drove again from seven metres out and Bury’s creaking defence was breached when prop Tom Belcher could not be halted from a few feet out.
Despite being down to 14 men, Bury scored two tries in the closing five minutes of the half.
Matt Edison and Tristan Rawcliffe made good ground down the middle of the park to earn Bury a penalty.
The ball was kicked to the corner, but instead of going for the forward drive they spun the ball wide for Tim Mann on a great angle to take it and score, with Henley-Hunter kicking the conversion to put Bury 12-8 in front.
Chichester looked vulnerable to the pace and power of Greg White and Mann in the midfield and were made to pay again on the stroke of half-time when a clearance kick did not find touch and two quick passes released Mann, who drew in two would-be tacklers before offloading to Solomon to outsprint his opposite number for a score in the corner.
The conversion was missed, but Bury had a nine-point advantage to defend into the second half.
However, the Suffolk side did not look comfortable and knocked on straight from kick-off before Jack Bentall rumbled over for a try converted by Gray.
The confident and upbeat mood of the Bury players that had left the field at half-time had gone within three minutes, but they did try to assert some control.
Michael Sage was unlucky to see a penalty come back off the upright, but he was successful a second time after 56 minutes.
White had twice made good ground and on both occasions Chichester transgressed at the rucks, prompting referee Peter Coulthard to issue a final warning to Chichester skipper Ben Polhill.
Chichester had clearly changed their game plan and gone down the route of keeping the ball tight with the forwards, which was paying dividends as the strangely-subdued Bury forwards failed to respond.
The Bury scrummage was dismantled on several occasions and Chichester camped on the Bury try line.
Wave after wave of blue-striped attacks were repelled by valiant defence for almost 10 minutes until finally Belcher again could not be stopped from three metres as the home side forwards powered him over in the corner.
Gray could not convert and it stood at 20-20 with 10 minutes to go, but Chichester smelt blood and a final surge at the Bury line earned them a match-winning penalty that Gray kicked to hand them a deserved triumph.