The Bulls blasted open what had been a tense, tight contest with six unanswered tries after the break, two of them to Shontayne Hape to complete his hat-trick.
Leeds had started brightly, pinning Bradford back in defence until their relentless pressure brought an early breakthrough when Kevin Sinfield kicked for the wing with awesome precision and Lee Smith beat the mighty Lesley Vainikolo to the ball for a try that showed what a cool customer he is.
Bradford spent plenty of time pressing after that, but did not find the killer touch until the 26th minute, when their left-wing partnership of Hape and Vainikolo clicked into gear.
Hape fed Vainikolo and, although the wing man was stopped on the line by a tremendous tackle from Sinfield, Hape had the presence of mind to back-track and force his way over.
There was a more worrying moment for Leeds soon after with Senior's injury - not the sort of thing that is needed eight days before a major final.
Leeds were still reeling from that when the Bulls opened them up again, Leon Pryce taking Iestyn Harris' pass and going through a high and ineffectual tackle from Richard Mathers to set up Andy Lynch.
It was Lynch who lost the ball in the tackle two minutes before half-time to enable Leeds to strike back, Ali Lauitiiti picking up and Sinfield racing through a static defence, also kicking the goal to leave the Rhinos just two points behind at the break.
Iestyn Harris' long pass, missing out two men, gave Jamie Langley the chance to increase the Bulls' lead early in the second half and that began the landslide.
Deacon managed to spin out of a two-man tackle and take the Bulls clear, Smith then made a mess of Harris' kick and, from that possession, another probing Harris pass sent Hape in for his second. Robbie Paul then made it three in four minutes when he latched on to Pryce's break.
Hape rounded it off with his third try as Bradford reasserted their old supremacy over their neighbours at just the right time to underline what a threat they could be in the play-offs.
In last night's other match, Salford beat Wakefield 37-0 with Anthony Stewart scoring a hat-trick.
Leeds: Mathers; Smith, Walker, Senior, Bai; Dunemann, McGuire; Bailey, Diskin, Ward, Ellis, McKenna, Sinfield. Replacements: Burrow, McDermott, Jones-Buchanan, Lauitiiti.
Bradford: Withers; L Pryce, B Harris, Hape, Vainikolo; I Harris, Deacon; Peacock, Henderson, Fielden, Meyers, Johnson, Radford. Replacements: Vagana, Paul, Lynch, Langley.
Referee: Ashley Klein (London)Reuse content