Winger Danny Schofield scored two and made the other as Huddersfield Town surged back into the third division's automatic promotion places.
Schofield put Town ahead on 51 minutes when he controlled Andy Booth's knock down from a Tony Carss' free kick before blasting past City keeper Roger Freestone.
And he sealed victory five minutes from time when he raced around Freestone to net from close range after Pawel Abbott's through ball split Swansea's defence.
Schofield has now scored eight goals this season and kept a fine individual display by setting up Anthony Lloyd in the last minute for a cheeky lob over Freestone from about 12 yards.
It was nothing less than Huddersfield deserved for a commanding performance in which they restricted the visitors to only one shot on target.
In fact the home side should have been at least two goals up in the opening 15 minutes but Booth, Carss and Abbott all missed easy chances early on.
Swansea defender Kristian O'Leary was the central figure as the visitors resisted incredible pressure during this spell and on several occasions he denied Booth and Abbott with a crucial last ditch tackles.
But unfortunately it was O'Leary's mistake that finally presented Huddersfield with the chance to go in front.
He lost Booth as Carss whipped in a free kick into the Swansea box and the wily veteran former Sheffield Wednesday striker headed the ball into Schofield's path to create the opening goal.
At the other end Swansea, whose play-off hopes have faltered following a run of only one win in seven games, rarely threatened.
Midfielder Roberto Martinez blasted over in the first half and it was not until substitute James Thomas forced Huddersfield keeper Paul Rachubka into a save on 66 minutes that Swansea got a shot on target.
That effort came in the middle of Swansea's only real spell of pressure but it was never going to be enough against a side who seem destined to secure automatic promotion.