Dulwich remain top, three points ahead of Maidstone, but have forfeited their game in hand. They will be bitterly disappointed by the result, having led 2-0 when an earlier attempt to play the game had to be abandoned.
Leatherhead stay in seventh place but are only two points away from the play-off positions with two games in hand on the sides immediately above them.
Fourth-placed Faversham moved closer to clinching their own play-off spot, recovering from an early double blow to win 4-2 at Crawley Down.
Fast-starting Anvils were 2-0 up in four minutes with strikes from Gabriel Odunaike and Luke Blewden, but Lynden Rowland responded quickly to make 2-1 after six minutes.
Renford Tenyue levelled the scores midway through the first half and Darren Marsden put Faversham in front soon after the break. Tenyue clinched it in the closing stages.
Trevor McCreadle fired a hat-trick as Horsham beat Chipstead 4-1 to leap six places in the table, from a perilous 21st to a comfortable 15th. Ray Freeman was also on target, and Tom Jelly netted a late consolation.
It grows ever grimmer for bottom club Walton Casuals, who are now six points adrift with only three games left to play.
Second-half goals by Pat Harding and Sam Fisk gave Burgess Hill a 2-0 home win over Herne Bay while a Fabio Saraiva double saw Merstham to a 3-1 victory over visitors Eastbourne, who took an early lead through Dan Smith but were pegged back by Lee Newman.
Keep up-to-date with our exclusive email newsletters.
Subscribe