Nahki Wells teammate winger Sean Scannell was involved in both Huddersfield goals as Brentford's five-match winning streak came to an end in a 2-1 defeat at the John Smith's Stadium.
Scannell, who signed a two-year contract extension last month, lashed the ball in from a tight angle on 18 minutes from a pull-back by Wells.
The move saw Jack Robinson beat fellow full-back Moses Odubajo down the left and crossed for Wells.
His pull-back from the near post ran too far for Grant Holt in the middle but Scannell raced in at the back to drill home.
Holt put Robinson away down the left on 48 minutes and it was his byline cross that led to a second goal for Huddersfield.
Scannell threw himself at the ball having steamed in from deep but he was beaten to it by Brentford's Jake Bidwell - who headed into his own net.
It helped end a five-match winning run for Brentford which had seen boss Mark Warburton named November's manager of the month.
Derby, Nottingham Forest and Fulham were among the teams Brentford toppled in a surge to third in the table.
They showed how they did it with a slick attacking display that saw them unlucky to be behind at the break.
Alan Judge, who fired wide early on, was denied a goal on 14 minutes when his deflected shot was acrobatically tipped over by Town keeper Alex Smithies.
He also parried a stinging drive which Bidwell struck with the outside of his right boot on 22 minutes.
Brentford created further chances for Alex Pritchard and Championship player of the month Andre Gray but they then fell behind against the run of play.
The home side had claims for a penalty waved away on 32 minutes when Conor Coady was felled by Odubajo.
Brentford's keeper David Button spilled a 25-yard drive from Jacob Butterfield and Coady went down as he tried for the rebound.
Gray, Brentford's eight-goal top scorer, fluffed a great chance to equalize in first half stoppage time.
Bidwell put Pritchard in down the left and his defense-splitting pass left Gray in the clear but he scuffed his attempted close-range shot into the turf.
Huddersfield started the second-half like a freight train but though they doubled their lead they never properly killed Brentford off.
Wells, eventually replaced by fit-again striker James Vaughan, missed several good chances, including on 63 minutes when he fired wide from Coady's pass.
REGGIE LAMBE
Adam Murray was denied victory in his first match as permanent manager of Reggie Lambe and his Mansfield Town teammates when Kwesi Appiah struck in stoppage time to earn Cambridge a 2-2 draw and set up a replay.
Lambe played the 90 minutes for Mansfield Town.
The visitors made the perfect start, taking the lead inside three minutes when top scorer Rakish Bingham beat Chris Dunn with a free header following Robert Taylor's cross from the left.
Richard Money's side were level in the 10th minute when Tom Champion dispossessed Simon Heslop and fed Luke Chadwick, who slid the ball past the onrushing Sascha Studer.
It looked like Mansfield were going to steal the result nine minutes from the end when Champion diverted Taylor's free-kick into his own net under pressure from close range.
But Appiah pounced in the second minute of added time. Having previously been denied twice by good Studer saves, the striker ran onto Liam Hughes' knockdown to rifle home a dramatic leveler.
Mansfield had almost made the game safe moments earlier when substitute Fergus Bell was denied by a splendid tip-over save from Dunn, but now they must go again in their bid to reach the third round.
