After a goalless first half in terrible weather conditions, the Black Cats came under pressure at the start of the second half.
Yet it was the visitors who took the lead ten minutes after the interval when Alex Pritchard scored against his former club.
Manchester United loanee Amad then added a second in stoppage time.
Our Sunderland writer Phil Smith has dished out his player ratings from The John Smith’s Stadium:
5. Dennis Cirkin - 6
One or two moments where Huddersfield got the better of Sunderland down his flank but especially late on he defended resolutely. 6 Photo: Frank Reid
6. Corry Evans - 5
Uncharacteristically sloppy in possession at times and was lucky that didn’t cause more problems on a couple of occasions. Broke play up well at times but not his best game. 5 Photo: Stu Forster
7. Elliot Embleton - 5
Couldn’t really get into the game from his deeper position and certainly not in the advanced areas where he can really hurt teams. 5 Photo: Frank Reid
8. Patrick Roberts - 6
Apart from one run he couldn’t offer much in the first half and in truth was short of his best for most of the game, but still produced a big assist for Pritchard’s goal. 6 Photo: Martin Swinney