Leeds had the chance to reduce St Helens lead at the top of the table to just two points, and did so in style thanks to a largely one-sided first half performance that yielded 30 points.
But Hull showed tremendous fighting spirit to come within seven points of Leeds, before the Rhinos ended the match with a superb try from rugby union bound Lee Smith.
Ryan Hall set the ball rolling with two superb tries inside the first eight minutes, diving over from short range for the first, whilst narrowly escaping touch for the second.
Danny Tickle did give Hull a little bit more confidence ahead of the second half with a try six minutes before the hooter.
But Leeds continued the second half as they did the first, with Ashley Gibson crashing over – converted by Sinfield for his sixth conversion out of six – to make the score 36-12.
That only stimulated Hull to attempt the seemingly impossible, as they scored three converted tries sandwiched around a Rob Burrow dropped goal.
Burrow’s dropped goal ensured Leeds had some comfort, but they were rattled when Hull scored again after Mike Burnett powered over.