Worthing will be playing in the Sussex Cup next season after winning their play-off against Horsham.
A change of rules as a result of East Grinstead and Lewes coming back into the competition this season has resulted in end of season play-offs to decide who will join them next year.
The four semi-finalists are guaranteed places in the eight-team Sussex Cup together with the Plate finalists, which are Eastbourne and Penguin.
That has left Worthing, Horsham, Mid Sussex and Crawley playing off for the remaining two slots.
Worthing won 3-2 in their play-off against a depleted Horsham side on Saturday. Captain David Edmondson and Andy Gough gave Worthing a 2-0 half-time lead.
Horsham fought back with goals from skipper Richard Lowe and Michael Roper levelling but Worthing grabbed a winner through John Massie.
Lowe said: "We were missing so many players. We played all right and should have got something out of it but I am not too displeased.
"It will be pretty good to play in the Plate and get some confidence back rather than being hammered by Lewes or East Grinstead."
The second play-off between Mid Sussex and Crawley takes place on Sunday April 27.
Chichester will meet East Grinstead in the Sussex Under-21 Cup final after both emerged as group winners in the tournament at East Grinstead on Sunday.
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