The visitors took the lead in the 9th minute when right back Peter Brackley overlapped to cross from the byeline for skipper Mark Burt to send a powerful header past United keeper James Courtnage.
The hosts were unlucky not to equalise soon after when a downward header from Tom Hill hit the base of the post and then minutes later, Roni Joe's header was held at the second attempt by Worthing keeper Matthew May.
It was 2-0 in the 31st minute when Burt punted upfield and Ben Carrington shrugged off the challenge of Peter Clifford before coolly slotting past Courtnage.
It was a greatly improved United showing in the second half and they pulled one back in the 61st minute when Joe outpaced his marker before curling his shot past May for his 13th of the season.
The Ducks pressed for an equaliser throughout the second half and deserved to get something out of the game but their rotten luck was just about summed up when sub Stephen Callinan hit the bar late on.
David Figg