The South Londoners led at the break – Luke Wanadio opening the scoring just before the interval from the spot. But they ended up losing 2-1 despite having a one-man advantage with the home side having keeper Jasper Sheik sent off after 39 minutes.
Andrew Briggs (with a penalty) and Luke Robinson scored twice in six minutes just past the hour to upset the odds in the Isthmian League Premier encounter.
“We missed two great chances in the first half,” an irate Hayrettin lamented. “Then we got a penalty that we deserved and then it’s like the boys decided to do what they wanted to do in the second half [against] 10 men and not listen to what we asked them to do.
“That’s the crux of it. We didn’t turn them, we didn’t put balls into areas we played sideways and we started going backwards. We didn’t put them under pressure. We didn’t put the ball in the box. Didn’t compete at all.
“Obviously I’m the manager and the buck stops with me, but I just couldn’t believe what I was watching.
“You go 1-0 up against 10 men, you’ve got to control the game and we haven’t done that. They controlled the second half. They wanted it more than us and I feel we let everybody down today.”
Hayrettin will be looking for a reaction in the New Year’s Day visit to Cray Wanderers’ Flamingo Park. Wanderers beat Hendon 1-0 at the weekend, Joshua Williams scoring in the 90th minute.
Meanwhile, Cray Valley (PM), were involved in a corker of a clash at Cheshunt which ended in a 4-4 draw. But the Millers were left frustrated after conceding a 93rd minute equaliser and having skipper Kiki Oshilaja sent off in conceding a late penalty.
They also led four times, with Dan Bowry giving them a third-minute lead and Freddie Parker, Denzel Gayle and Tom Beere all finding the net.
But the hosts replied through Tommy Wood, Vas Vasiliou and Tobias Braney and although Max Ovenden saved the penalty conceded by Oshilaja, Wood bagged a leveller from the resulting corner.
The Millers travel to Carshalton Athletic on New Year’s Day (3pm kick-off)
In National League South, Welling United remain just above the relegation quartet but a 1-0 home defeat to Chelmsford City leaves them still a bit close for comfort – albeit with an eight-point cushion.
The Boxing Day clash at Park View Road looked to be heading for a 0-0 draw but youngster Osman Foyo – on loan from Premier League Ipswich Town – grabbed a winner for the visitors five minutes from time.
Welling did come close in injury-time when sub Zain Walker’s half-volley took a nick off a defender which took it just over the bar, but Rod Stringer’s men were left empty-handed after a hard-fought battle.
Welling travel to third-placed Maidstone United for their New Year’s Day match (3pm).
DULWICH PICTURES FROM BOXING DAY MATCH: ROB AVIS