Ian Draycott's first-half double saw Maidstone beat Sittingbourne 2-1 in front of almost 2,300 fans at the Gallagher Stadium.
Skipper Shaun Welford had a hand in both goals on his return from suspension as United's flying start was rewarded with two goals in 20 minutes.
Nick Treadwell replied deep into injury-time but United saw out the remaining seconds to cut Dulwich Hamlet's lead at the top of Ryman League Division 1 South to two points.
Third-placed Hythe fought back from two goals down but lost 3-2 at Faversham.
Jake Hobbs and Dave Cook cancelled out first-half efforts from Aaron Lacy and David Botterill, but Darren Marsden scored Town's winner in the 65th minute.
Darren Smith struck four minutes from time as Folkestone came from behind to beat Whitstable 2-1.
Jake Beecroft gave the visitors an early lead at Cheriton Road but Richard Atkins equalised before Smith earned the points.
Herne Bay's match at home to Ramsgate was postponed due to a waterlogged pitch.
Substitute Malachi Hudson scored an injury-time winner as Thamesmead beat Aveley 3-2 at home in Ryman League Division 1 North.
Ashley Probets, with a penalty and a 25-yard free-kick, twice put Mead in front.
Chatham had Matt Newman sent off for two bookable offences in their 5-1 defeat at Tilbury. Brad Potter scored the only goal for the visitors.
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