It was a familiar story with a bright start undone by lax defending and a late revival coming only after the damage had already been done.
What makes it all the more frustrating is that their away form is excellent, with The Tye still unbeaten away from Piddinghoe Avenue. How a ground which for the past three seasons has been a fortress has become such a weakness is almost incomprehensible, and it must be starting to concern Shaun Saunders.
The most plausible explanation is that teams have got wise to the fact that Peacehaven are now playing a far more expansive style of football, and are sitting off and putting pressure on a defence who don't appear entirely comfortable with the style. That was certainly the case against YMCA, who profited from two defensive errors to establish a lead which proved impregnable, despite a late onslaught.
Harry Coker and Aaron Gunn came into the starting line up in place of Ashley Rees and Dave Altendorff against an experienced visiting side and Peacehaven made an encouraging start, with Wes Millis and Rob O'Toole both going close as they established an early grip on the match.
Not for the first time in recent weeks that grip loosened as the half wore on and frustration set in, and that frustration was compounded as the visitors took a surprise lead. Possession was squandered on the edge of the box and Dean Wright seized on the loose ball to stride in on Jake Buss and slot past the keeper.
Peacehaven's troubles increased at the start of the second half when a long clearance wasn't dealt with and Wright nipped in for his second goal of the afternoon.
The home side now had a moutain to climb, and there was little sign of them starting the ascent. The introduction of Matt Nuttman at last provided a spark to a listless attack, and it was from his cross that Carl Dunk volleyed 'haven back into contention.
That sparked a late revival, but despite creating considerable pressure Peacehaven were unable to make the breakthrough, and were left with another damaging setback.