Diss head coach Phil Sharpe blamed his side’s ‘unbelievable silliness’ for slipping to a fourth consecutive defeat in London One North.
The Mackenders-based outfit have come up against some of the league’s best sides in recent weeks, but Old Haberdashers began the weekend below the Norfolk side in the table.
However, Diss struggled for long spells of the match and must now look to put it right at home to Ruislip tomorrow (2.15pm).
“Ruislip have a very good set of centres,” said Sharpe. “I was amazed they were floundering at the start of the season, but they have pulled themselves up the table.
“They came within a few points of turning Bury over, so it will not be an easy game.”
Reflecting on the 20-14 loss to Old Haberdashers in which John Laurie and Warren Wilby scored tries converted by Nick Harding, Sharpe said: “We should have won that match and let ourselves down — it was just unbelievable silliness from us.”
Diss look set to be without lead goal-kicker Chris Beaird tomorrow after he sustained a neck injury in an off-the-ball incident.
Meanwhile, flanker Jason Thomas has returned home to New Zealand while Warren Wilby is carrying a wrist injury, but should feature.
Diss are eighth in London One North, two places and 12 points above Ruislip.