A last-minute winner saw Brighton go down 2-1 to Hastings Town at The Pilot Field.
The Dr Martens League side came back from a goal down, thanks to two goals from veteran Terry White.
A Paul Brooker goal was not enough to prevent an upset as White scored twice in the last ten minutes.
The Albion fielded a strong line-up but their non-league opponents showed lots of spirit and had plenty of chances.
The match had got off to a quiet start before tempers flared in the 12th minute.
A foul by Hastings midfielder Duncan McArthur led to a brawl which saw half the players on the field involved.
The referee had a stern word with McArthur and Albion's Richard Carpenter but would probably have shown at least a yellow card or two in a more meaningful game.
The Seagulls had the better of possession early in the first half but didn't look particularly sharp in front of goal and rarely troubled keeper Shwan Jalal.
Indeed, it was Hastings who came closest to scoring before the break, and the non-league side hit the woodwork twice as they began to hold their own.
On the half hour, Paul Jones hit the woodwork and the same player was denied by the post after 42 minutes.
Duncan McArthur fed the ball to the centre forward who chipped Kuipers only to see the ball rebound off the inside of the post into the relieved keeper's arms.
Gary Hart entered the fray after the break and livened up Albion's attack.
But it was the impressive Brooker who put the Seagulls ahead after 61 minutes.
There was a hint of offside as he ran on to Charlie Oatway's chipped through ball but the flag stayed down.
Brooker's first shot was parried but he turned the rebound into an empty net.
A Hart header and a speculative shot from Oatway both flew narrowly over the bar as the visitors looked to extend their lead.
But Town levelled after a foul on Paul Jones led to a penalty on 81 minutes.
White despatched the penalty in emphatic fashion and went on to head an unstoppable last-minute winner from a Danny Simmonds' corner.
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