Mick Vipond again shuffled the pack for Saturday’s game, but Berkhamsted went down 1-0 at Dunstable.
Ex Leverstock Green top scorer Louis Bircham made his first start for Berko and Jamie Gavin was also fit to return in midfield and Alex Foster played at left back because James Baldry was ruled out with suspension.
The first half was even and there were no goals.
It looked like a set-piece would be the most likely source of a winner with the two midfields cancelling each other out.
So it proved in the 70th minute when Leon Cashman arrived unchallenged to net with a header after a free kick was floated in from the left wing.
Berko used all three substitutes and attacked hard trying to rescue a point or more.
However, the tall Richard Perks looked solid in the home goal, but had to use his foot to save a low shot from Chamberlain.
Berko thought they had levelled but the assistant referee ruled the ball had not crossed the line as it came down off Chamberlain.
A snapshot from Chamberlain seemed to defy the laws of physics in the closing stages as it hit one post and ran across the length of the goal line before passing the other post and spinning over the byline, confirming it was not to be Berko’s day.
On Saturday, fourth-placed Berko are at home to rock-bottom Holmer Green (ko 3pm).
Berko Reserves beat Hanworth Villa Reserves 7-0 at home in the Suburban North.
Berko are now nine points clear at the top. Pierce Kelly grabbed a hat trick and Jay Caines scored twice with Tom Shaw and Kiefer Shuttleworth also netting.