Littlehampton let slip a two-goal lead Broadbridge Heath dumped them out of the Peter Bentley Cup with a 3-2 defeat which was decided by a 90th minute goal.
Both sides were reduced to ten men after red cards to Alex Laing and Marlon Maxell.
Heath, who were already on the comeback trail through Tim Martin’s goal, levelled through Danny Attwater, before Fender’s late winner.
After 28 minutes Littlehampton’s Lee Garnham set up Kieron Playle-Howard to finish clinically.
The home side continued to cause problems and forced Michael Chester into another sharp block from Shay Wiggans.
Four minutes before half-time, Chester could only parry a cross and the resulting scramble led to Playle-Howard doubling the lead.
Littlehampton began to get on top again in the second half with the lively Lucas Pattenden testing stand-in right-back Flack.
Then on 75 minutes Laing was shown a red card after going into a challenge studs up, though it was not clear whether this was the result of a second yellow.
Just when Heath were getting on top they suffered a set-back when Maxwell received a second yellow card and was dismissed.
A series of corners eventually ended with ball being cleared back to McDermott whose inviting cross was powered home by Danny Attwater to bring the scores level with eight minutes remaining.
Then in the 90th minute the otherwise quiet Tom Howard-Bold lost two markers in midfield and sent a pass through to Fender, who outpaced the defence and finished clinically to send Heath through.