The Whites snatched an undeserved lead in the way that champions tend to do, and when the Terriers needed something extra, the tank was empty. By the time three good chances fell their way in the latter stages, Danny Cowley's side has been mentally beaten too.
The football Leeds played in their 2-0 win – their sixth in a row – was not impressive, but their resilience was. It is a quality that can make a difference when the end-of-season trophies are handed out.
For all the Terriers's determination, they lacked it.
Wounded after their mauling at Bristol City seven days earlier, a depleted Huddersfield came out fighting.
Right from the off, they played the game like a proper derby, ignoring their absentees to race out on the front foot. Steve Mounie was a constant aerial threat in his first start of the season, and he did not lack support. The positivity of wingers Elias Kachunga and Josh Korona meant that at times their formation was 4-2-4, pushing back Leeds's wing-backs.
Right-back Demeaco Duhaney was another making his first start of the campaign and second overall, after being called back from Boston United, while Florent Hadergjonaj filled in on the other side of the back four.
Leeds had their injury problems too, and they seemed to cause them more tactical plans.
The plan all week had been for centre-back Ben White to anchor the midfield with Kalvin Phillips suspended, but when Liam Cooper felt his calf, it left White as the only specialist central defender.
He moved instead into the heart of a back three, although Kachunga and Korona forced it back into a five. That left a big gap between the defence and Mateusz Klich and Pablo Hernandez – the hole Phillips would normally fill. The Terriers dominated that area of the field.
There was plenty for referee Gavin Ward to keep an eye out for, Mounie wrestling with Luke Ayling in the wall at a free-kick conceded by Stuart Dallas's handball, a slap off the ball by Egzjan Alioski, Patrick Bamford c,laims of a Jon Gorenc Stankovic stamp, and a few tasty tackles and exaggerated reactions as Cowley in particular gave a running commentary on his view of it all from the technical area.
For all the early Huddersfield barrage, it was Leeds who hit the post in the 16th minute, Pablo Hernandez pulling back the sort of corner Teddy Sheringham used to thrive off, and Klich driving low and hard against the upright.
It seemed like the Whites were just starting to get to grips with Town, but it was not the case. Juninho Bacuna, his football as creative as his hair, skipped past White, pulled out into the position he had been training in all week and had a shot blocked. Three minutes later he floated a lovely curling free-kick, and Kiko Casilla needed an excellent save tip Mounie's header over. He forced another save a minute later, only to clash heads with Karlan Grant, the first of three injury worries for Huddersfield in the first half as Christopher Schindler and Bacuna also needed lengthy treatment.
When Casilla came out to the edge of his area to punch clear and collided with Mounie, Luke Ayling did brilliantly to touch Grant's shot over.
What chances Leeds had were snatched at, and Klich and Dallas were booked at the end of the half for tackles on Kachunga.
Josh Koroma produced some great footwork at the start of the second half, but Grant was unable to provide the touch to finish it. When a half-chance fell Leeds's way, Ezgjan Alioski brilliantly snaffled it.
Mounie's clearing header from Pablo Hernandez's 51st-minute corner teed up a volley smashed in.
Suddenly Huddersfield looked weary, and Leeds looked quicker and fresher in central midfield.
There was little they could do to change it, their bench having a grand total of one start for them this season, made by Rarmani Edmonds-Green in the League Cup before he went out on loan to Bromely.
It looked like one would be enough, but just to be sure, Hernandez got a second.
Kamil Grabara had made a good save from a Bamford header, Casilla an even better one going the wrong way to Koroma's header.
Hernandez stooped at the far post to head in the Harrison cross at the end of a sweeping move after 80 minutes.
Mounie, Grant and substitute Matty Daly all had very good chances after that, but Huddersfield's belief had gone.
Huddersfield Town: Grabara; Duhaney Schindler, Stankovic, Hadergjonaj; Koroma (Harratt 72), Bacuna, Hogg; Kachunga; Grant, Mounie (Daly 82).
Unused substitutes: Coleman, Edmonds-Green, High, Austerfield, Jackson.
Leeds United: Casilla; Ayling, White, Berardi; Dallas, Klich (Casey 85), Hernandez, Alioski; Costa (Douglas 85), Bamford (Nketiah 77), Harrison.
Unused substitutes: Miazek, Hosannah, Gotts, Clarke.
Referee: G Ward (Surrey).