Philippe Coutinho's deflected strike gave the visitors a half-time lead before second-half goals from Matty Cash and Calum Chambers put the game beyond Leeds' reach.
Fans started leaving their seats well ahead of the final whistle as the result looked sewn up long before the 90 minutes was up.
There was further cause for concern in the game's dying minutes as Junior Firpo was stretchered off the pitch by the Leeds' medical team, forcing United to finish the game with ten men.
Graham Smyth, the YEP's chief football writer, hands out the scores from a terrible evening at Elland Road.
13. Joe Gelhardt (sub)
4 - Showed fight, caused a problem or two but couldn't rescue Leeds from the slump after the second. Photo by Stu Forster/Getty Images.
14. Mateusz Klich (sub)
5 - Tried to get Leeds going forward but little came off. Picture by Jonathan Gawthorpe.
15. Simon Hooper (referee)
4 - Lack of consistency in the first half left Leeds incensed. Didn't have a huge deal to deal with but still managed to irritate both sides. Photo by George Wood/Getty Images.