Steyning Town caused an upset in the John O'Hara League Cup with a 3-1 win at first division Hailsham.
The second division side fell behind to a Scott French goal on four minutes but strikes from Tom Pickford, O'Neill and Martin Rowe turned the game on its head.
Manager John Bolingbroke said: "It wasn't a fluke. We played really well."
Arundel beat second division Oakwood 2-0 in a third round clash thanks to Barry Pidgeon's header and an own goal.
Mullets assistant-boss Wayne Flynn said: "It was never going to be easy but we went out there with the right attitude."
Oakwood had James Grant sent off in the second half.
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