Lee Novak's first-half brace helped Huddersfield to an impressive win at Yorkshire rivals Sheffield United.
The Terriers took the lead when Novak slotted home after Steve Simonsen parried Danny Ward's effort.
The Blades almost levelled when Chris Porter met Matthew Lowton's cross, but the striker shot wide of the post.
Novak fired in a second when the United defence failed to clear their lines before Oscar Gobern headed in Ward's corner from close range.
Sheffield United's half-time substitute Ched Evans went close after the break from a free-kick.
Huddersfield's victory extended their impressive unbeaten run to 33 league games, while the Blades lost top spot in League One to Charlton on goal difference.
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Sheffield United boss Danny Wilson told BBC Radio Sheffield:
"I thought it was a good game of football to be honest but, when you're three-nil down at half-time, it becomes a very difficult game from our point of view.
"We've not looked very vulnerable this season. We've looked very strong at the back and that's been one of the strong points we've had.
"We've had chances and better chances than they've had but we've not managed to find the back of the net."
Huddersfield Town manager Lee Clark told BBC Radio Leeds:
"My team have made me extremely happy and proud. I thought we were sensational at times.
"At other times we had to dig deep, block shots and my goalie had to make saves, but we've done it.
"We've kept a clean sheet away from home, scored three and could have had a few more. I couldn't be more pleased with that.
"Going away from home to a team that's had a fantastic start like they have and the players and manager they have, for us to do that to them is very pleasing."