Manager Steve Bruce likened Newcastle's defending to "something you see on a park on a Sunday" after they conceded three times in the last 13 minutes at Leeds.
The Magpies were in the game at 2-2 until the 77th minute when right-back Stuart Dallas stole in at the far post to convert Mateusz Klich's ball from the left.
In searching for an equaliser, the visitors ditched their counter-attacking tactic only to be twice given a taste of their own medicine when Ezgjan Alioski fired in from substitute Pablo Hernandez's pass after a swift break before Jack Harrison thumped home a brilliant fifth on the run from 25 yards.