Haywards Heath are planning for a major Tetley's Bitter Cup test at Newbury after reaching the second round proper.
But Worthing's hopes of a home tussle with Clifton were thwarted as they lost just 9-8 at home to Cheshunt on Saturday.
Heath were comfortable 38-10 winners at Wimbledon and now face a Newbury side who currently lead National League Two, effectively the third division of English rugby.
Skipper Henry Goodburn saw his side produce superb defence on Saturday before running in four second-half tries and admitted: "A test like this is what we have needed for a while.
"It will be a great for the club and there is no reason why we cannot go there and give a very good account of ourselves."
Owen Ashton's three penalties and a smartly taken Jon Graham drop goal gave Heath a 12-3 first half lead playing with the wind but they then had to tackle tenaciously as Wimbledon staged an onslaught after the break.
The back row in particular stood up to the test and No.8 Nick Dinsdale then helped Giles Goodburn to the first of his two tries once the storm had been weathered.
Adrian Cassidy and Alex Meredith also on the scoresheet.
Worthing skipper Mike Imrie was bitterly disappointed to miss out after a 73rd minute try by Neal Weston cut the gap to just a point and set up an exciting finale.
He admitted: "Cheshunt were much more streetwise than us. They got away with a lot in front of the referee, but when we tried it we got caught.
"Neither side created a lot of opportunities but they were worthy winners on the day as we failed to adapt to their tactics."
Andrew Clements' three penalties proved decisive. Ben Coulson kicked one but hit the post with another attempt and was also unable to convert Weston's try from wide out.
Jamie Newhouse and Danny Piggott were both yellow-carded for Worthing, who defended strongly to keep themselves in the contest It was also a busy day of league action and champions Brighton got off to flyer in London Three South East.
They overcome a slow start to score an encouraging 38-11 win at Cranbrook, the only side to interrupt their near perfect campaign last time out.
Skipper Gary Henderson was delighted with a six try display and said: "We really took them to pieces.
"The style of rugby we are playing is very good. We are putting together phases of play for much longer."
Back row men Craig Taylor, Simon Peters and the outstanding James Jefferies all scored, along with Geraint Jones, Martin McDonagh and James Lewis. Paul Marks topped up the tally with kicks.
East Grinstead, who go to Waterhall on Saturday, lost 40-10 to a Tunbridge Wells outfit who look like being one of the sides to catch this season.
Lewes's troubles continued as they went down 33-10 at Sidcup. The hosts scored all their points before Lewes replied with a Tim Hemsley try plus a conversion and penalty by Huw James.
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