Former Crystal Palace striker James Vaughan piled the pressure on Ian Holloway by hitting the only goal of the night at the John Smith’s Stadium.
The Terriers’ 1-0 win was their first in 13 Championship games, while the Eagles’ concerning run of League form now stretches to just two wins in 12 games.
Moreover, Palace have managed just four goals in six January games, including a Glenn Murray penalty, whereas December’s record stood at 11 goals in six games.
Vaughan, who made 30 appearances for Palace while on loan from Everton scoring nine goals, grabbed the decisive goal on 65 minutes beating Julian Speroni with for his fifth goal of the season.
Holloway replaced new boy Jazz Richards and Jonathan Parr with Aaron Wilbraham and Jermaine Easter in an effort to grab an equaliser – however, despite Easter flashing a header wide, there was to be no salvage operation.
There was controversy at the final whistle when an apparent tunnel bust-up between Palace skipper Mile Jedinak and the Terriers’ late substitute, and former Palace favourite, Alan Lee left Jedinak nursing an eye injury.
Holloway was so incensed with the alleged incident he declined to take part in the normal post-match press conference.
Palace now turn their attention to Saturday’s London derby with Charlton Athletic at Selhurst Park – after the small matter of the January transfer window is done and dusted.