Gosport’s play-off bid took a knock as their 23-match unbeaten league run was ended in a shock loss at home to Arlesey Town.
Borough were the better team throughout at Privett Park but could not find the breakthrough.
And they were left empty-handed when the visitors grabbed a late winner to leave their opponents shocked.
A bumper crowd greeted Borough from the start and, with fans still coming through the turnstiles, Brett Poate fired in a shot that went inches over the bar.
More pressure followed and the hosts appealed for a penalty as Dan Wooden went down under a late challenge chasing Sammy Igoe’s inspired through ball into the penalty area.
The referee rejected the calls, though. And as play continued, Arlesey broke quickly to the other end where keeper Nathan Ashmore had to be at his best to claim Chris Dillon’s shot.
On 20 minutes, Arlesey shot-stopper Nathan Abbey somehow turned over Wooden’s goalbound header from Dan Woodward’s cross.
Rory Williams then sent Woodward clear to blitz a shot wide of the far post.
Igoe continued to be at the best of what Borough created and even found time to get ahead of his strikers to power in a shot that Abbey saved at his near post.
Arlesey offered little threat but defended well enough to ensure it was all square at the break, although Williams did have the ball in their net, only to have it ruled out for an earlier infringement.
On 55 minutes, and with Gosport continuing to dominate every area of play, Williams went clear to beat Abbey with a shot that fizzed narrowly over.
Arlesey continued to probe in rare forays but should have taken a shock lead when Ashmore parried Ollie Thorne’s shot, only for Leon Hibbert to follow up and blaze over with the goal at his mercy.
In an effort to add more bunch up front, Borough boss Alex Pike brought Justin Bennett off the bench to take over from Woodward on 65 minutes.
The striker went desperately close to giving his side a deserved lead with a cross-shot.
Then, after Poate was booked for a high challenge on Dillon - and Ashmore had done well to save the resultant free-kick by Hibbert - play broke to the other end and the visitors went ahead.
It was a soft goal that proved to be the match-winner, with striker Dillon claiming it after his mis-hit shot took a couple of deflection and beat Ashmore.
Gosport battled on, only for Arlesey to hold out and end their proud unbeaten run.
The positive news for Gosport, though, is that they occupy the remaining play-off place after near-rivals Weymouth, Barwell and St Albans all failed to win.
Southern League premier division
GOSPORT BOROUGH 0
ARLESEY TOWN 1 (Dillon)
Gosport Borough: Ashmore, King, Poate, Cook, Woodford, Dunford, Igoe, Smith, Wooden, Williams, Woodward. Subs: Ender, Martin, Wilson, Bennett.
Arlesey Town: Abbey, Mawer, Cook, Blackett, Frater, Prosper, Thorne, Hibbert, Dillon, Roberts, Goss. Subs: S Farrell, B Farrell, Marsh, Hatch, Bussey.
Referee: Stephen Finch (Southampton).