Mark Robins, once described by Sir Alex Ferguson as Manchester United's most natural finisher, and Andy Rammell, who used to understudy Robins in the reserves, scored the first-half goals for Walsall which ended Huddersfield's winning streak at six matches.
The Midlands side, who had prevailed only once at Bescot Stadium since achieving promotion last May, thus halted their own run of seven games without a victory. In doing so, they also proved they could beat clubs other than their immediate neighbours. Their only previous victims were Wolves, Birmingham and West Bromwich Albion.
Bruce, whose team face the leaders, Manchester City, at Maine Road at the weekend, commendably declined to deny Walsall the credit they were due. "We got exactly what we deserved - and that was nothing," the Huddersfield manager said.
"When you are riding high, people are waiting for you. There were too many performances out there which didn't live up to those of the last few weeks."
Ray Graydon, the Walsall manager, said: "Make no mistake, we have beaten a very good side. Huddersfield's front two are as good as you get in this division, but we deserved it."
In fairness to Bruce's players, they ran into a goalkeeper, in James Walker, who was on peak form. Walker made a string of agile saves in the closing stages, notably from Marcus Stewart and Scott Sellars, yet Walsall were in no mood to relinquish an advantage secured with a combination of enterprise and endeavour.
Their first goal arrived after only seven minutes. Dean Keates' deftly chipped pass found Robins lurking unmarked 15 yards out, whereupon the widely travelled forward lobbed it instantaneously and with equal subtlety beyond Nico Vaesen.
Walker's smothering save prevented Clyde Wijnhard from claiming an equaliser almost immediately, but Walsall pressed forward with a panache which belied their position in the relegation zone. They doubled their lead seconds before half-time, when Rammell rose, again unchallenged, to head in Chris Marsh's cross to the far post.
Walsall's ascendancy was epitomised by the sight of their debut-making Argentinian left-back, Diego Padula, nutmegging Chris Beech. While it was not always so easy, the watching Joe Royle must have enjoyed the irony of a pair of one-time Red Devils keeping his Blue Mooners on top.
Walsall (4-4-2): Walker; Marsh, Roper, Viveash, Padula; Wrack, Bukran, Keates, Matias; Rammell, Robins (Larusson, 87). Substitutes not used: Eyjolfsson, Barras, Gadsby, Emberson (gk).
Huddersfield Town (4-4-2): Vaesen; Jenkins, Dyson (Gray, h-t), Monkou, Vincent; Gorre, Irons, Beech, Thornley (Sellars, 55); Wijnahard, Stewart. Substitutes not used: Horne, Armstrong, Margetson (gk).
Referee: B Knight (Orpington).