Andrew Cook got a rare chance at outside half and grabbed the late drop goal which keeps Haywards Heath flying high.
Heath made it three wins from three in London One with an 11-10 home success over Harlow.
But they were in danger of a first home defeat in almost three years when Rudi Esterhuyse slotted an injury time penalty to put Harlow 10-8 up.
There was still time for Owen Ashton to be given a long-range penalty chance. A Harlow forward was given a lift by colleagues to prevent the ball from creeping over the bar, but knocked on in the process.
Cook slotted the decisive points from the subsequent scrum.
The 24-year-old, who normally operates at full back, admitted: "A few people thought that was it when they went back in front, but the referee played a stack of injury time.
"We got a good solid scrum and I just put my head down and got boot to ball.
"It was never going to be pretty but the ball went over and we were all rather relieved."
Despite the scoreline, both sides played some entertaining rugby. Prop Paul Prendiville scored an early try for Harlow but Ashton replied with a penalty.
Then home hooker Gordon Denslow made it a good day for the front row union when he charged down a kick and won the race to touch down.
Cook added: "I enjoyed the game. Harlow had a young side and played a university style of rugby, similar to us."
Worthing will be hoping to follow in Heath's footsteps by winning a title this season.
They made it two wins from two in Three South East but were not at their best as East Grinstead were beaten 22-12 in a scrappy contest.
Alistair Coombe, Danny Piggott and Steve Imrie scored tries with Tony Cruz kicking two conversions and a penalty.
Coach Ian Davies admitted: "We are not playing to the patterns I am trying to introduce yet."
Steve O'Reilly kicked four penalties for Gs.
Crawley celebrated a 29-25 win at home to Brighton, for whom the frustration continues after having two men sin-binned and squandering a 17-0 lead.
It has been a tough start to the season for both sides but Crawley pack leader Tony Parsons said: "The spirit we played with on Saturday was tremendous."
Darren Shadbolt, Lee Preston and new boys Joe Simpkins and Joe Smillie scored tries for Crawley. Andy Evans' boot completed the tally.
Brighton coach Merritt was unhappy to see skipper Mark Jenkins and scrum half Jason Tams yellow-carded for holding back players off the ball.
He said: "They were penalty offences but to have guys sin-binned was pretty harsh.
"It looked like a 40 or 50-pointer for us at one stage but heads went down."
Lewes went down 16-7 at home to Tonbridge Juddian. Full back David Tyrrell came into the line for a fine try which Huw James converted to give Lewes a 7-3 half-time lead.
Judds' pack then got on top and tries from threequarters Greg Ravilious and James Goldworthy settled the contest.
*Eastbourne are the comeback kings in London Four South East.
They followed their opening day rescue mission at Folkestone by snatching a late 20-18 win at home to Hove.
It is a perfect start for the promotion hopefuls but club press officer Graham Shiret said: "We are making hard work of it."
Andy Moore and Matt Bremer scored tries, with Moore adding a conversion and a penalty.
Then wing Rob Light popped up on the overlap to grab the winning try in the last two minutes.
Hove back row man John Oades scored a try in his first game as skipper but took a blow to the head in the process and had to go off.
Darryl Elliott also crossed after forward pressure and Phil Ward added a conversion and two penalties.
Bognor bounced back from their opening day shock at Hove by beating Beccehamians 29-3. In-form full back Andy Shipp collected three tries and two conversions.
Debut prop Anthony Johnson also crossed and there was a score by Tom Trenchard.
Uckfield somehow managed to lose 10-8 at home to Cranbrook. Nick Ridley scored a try and a penalty but missed our other penalties and also saw an attempt bounce back off the crossbar.
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