An under-strength Worthing beat East Grinstead 15-8 in their cup clash at Roundstone Lane but both sides appear to be attaching greater importance to their forthcoming league clash.
Steve Imrie put Worthing ahead with a try created by Adam Holloway and converted by Tony Cruz, although Steve O'Reilly managed a penalty before the break.
Back row powerhouse Paul Cox got Worthing's second try and Ali Wood later dropped a goal.
Mike Ayres' try rewarded a belated rally by Gs, who are promising a much more lively encounter at Saint Hill in the league on March 9.
Heathfield ground out a 3-3 draw after extra-time at Hastings and Bexhill and will go through as the away side.
Lewis Beale kicked a penalty for Heath, whose coach Herb Merritt admitted: "I didn't even realise we were going through until someone told me the rules a couple of minutes from the end.
"It was a poor game but we are asking a lot of smaller clubs to keep performing at a high level week after week."
Lewes made sure they avoided an upset as Seaford were seen off 37-13 at the Stanley Turner Ground.
Wing Paul Livesey smoothed their passage with a first half try hat-trick.
Dave Hemsley also got over as Lewes opened a 22-0 lead by the break.
Phil Eedes, Livesey again and Andy Turner also struck with Dave Tyrrell kicking a conversion.
Seaford's spirited second-half effort brought tries from the excellent Rob Impey and skipper Peter Joy. Andy Booth kicked a penalty.
Uckfield had an early scare in their 22-12 defeat of Pulborough when Matt Wormull touched down for the Sussex Two side.
Lee Evans, Anthony Monk and Bryan Huxley saw the hosts into a 15-5 lead at the break only for Gary Kidner to finish off a super move, with Andy Bates adding goal points. That made it 15-12 but replacement Russ Figg sent in Gareth Quay for a clinching try which Henry Hadow converted.
Quarter-finals: Haywards Heath v Uckfield, Heathfield v Chichester, Hove v Eastbourne, Lewes v Worthing. Ties to be played March 3.
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