Newcastle manager Rafael Benitez was left to reflect on a "really disappointing" performance as his side crashed to a second consecutive defeat to start life in the Championship.
Huddersfield served up an early-season shock as substitute Jack Payne struck a late winner in front of a sell-out St James' Park crowd that had arrived for the Magpies' season opener full of expectation following a summer of spending.
What they witnessed was instead a fully committed display from the visitors, who had seen Nahki Wells' opener cancelled out by Newcastle's £10 million summer signing Dwight Gayle.
"We weren't expecting this kind of performance, we knew Huddersfield would be difficult to break down but we didn't play at the level we wanted to," Benitez said.