Oldham wracked up their fifth successive win in the Second Division to leave former boss Mick Wadsworth feeling blue.
On his first return to Boundary Park since he was sacked at the end of last season, Wadsworth saw his new club swept aside.
He admitted: "Oldham are the best team we have played and our weakness in the centre of defence was highlighted to a large degree.
"We played quite well in the first half but finished it 2-0 down and the more you go after the game the more it opens up.
"It's obvious our scoring record has to improve and the last three performances have not been good.
"It's hard enough to come here with your best team available but we didn't have that and our financial problems will make it difficult."
When Wadsworth was Oldham manager he appointed Iain Dowie as his number two and Dowie got one over his former mentor as the Latics produced a superb attacking display.
They took the lead in the first minute when John Eyre fed ex-Terriers star Clyde Wijnhard, who fired a low shot into the bottom corner for his ninth goal in nine games.
And it was soon two as veteran winger David Eyres cracked a superb shot into the corner from 20 yards after a set-piece was only partially cleared.
Youngster Scott McDonald wasted a chance for the visitors and they were made to pay eleven minutes after half time.
Carlo Corazzin crossed from the right, Eyres headed down and Wijnhard tapped in from close range.
Huddersfield striker Andy Booth hit the post when it looked easier to score before Oldham sub Lourenco Da Silva finished the demolition job with a brilliant overhead kick from eight yards.
Dowie said: "He has the ability to do that kind of thing, but we have a lot of good players here and we have put ourselves in a very strong position."