Berkhamsted slumped to their first midweek defeat of the season amid stormy scenes at St Margaretsbury on Tuesday night.
The home side got an early goal when a shot from Ricky Light swerved past Carl Tasker, who got a touch, but could not prevent the effort from reaching the net.
It was then a matter of would Berko have the skill or brains to break St Mags down in the face of every time-wasting trick in the book, as they sat on their lead.
BJ Christie and James Baldry fired shots over the bar, while Lee Robinson was in inspired form in the home goal and pulled off a triple save to keep out Christie.
He also won a tackle with Christie and dispossessed him later in the same move, with the striker having a penalty appeal turned down.
Long throws from Josh Chamberlain picking out Ed Canham created pressure, but it was not Berko’s night for taking chances.
Berko’s midfield struggled for possession in the first half, but did better after the interval when Jordon Frederick came on.
Canham and Baldry were booked for fouls and the home side also picked up a couple of yellow cards.
Tempers were fraying and Chamberlain was booked for dissent to the assistant referee by the corner flag, before Robinson fielded a Christie header and a right foot shot from Chamberlain went wide.
Berko took off Courtney Massey and went to three at the back to try and attack, but the hole in the right of the defence was soon exploited when Joss Liliis scored a second.
Chamberlain headed wide and Canham headed against the bar from a Chamberlain corner as Berko battled to get back in it.
Within a minute of getting booked for dissent, Frederick was foolish enough to upend a home player to get an early shower.
To cap a miserable night for Berko, coach Kevin Taylor was sent from the bench for trying to get a ball back, as the match officials were unable to deal with the St Mags tactic of continually taking balls from the half way line to hide them in the dug out – just to hold up play.