ALTAY BAYINDIR matched axed Andre Onana for calamitous keeping as Manchester United suffered another defensive mauling.
Bayindir and Noussair Mazraoui blundered for goals as Newcastle run amok after the break to go fourth.
And it means United face a new historical low in terms of their league season – while the Magpies landed their first double over United since 1931.
Sandro Tonali capped a slick move by brilliantly lashing home the Toon's 24th-minute opener, via a deft volleyed through-ball from Alexander Isak.
Alejandro Garnacho matched that for precision with a left-foot leveller in off the far post.
But Harvey Barnes slotted home to deservedly restore the Magpies' lead soon after the interval.
And midway through the second period Barnes robbed the dozing Mazraoui to race clear down the middle before firing Newcastle's third goal high into the net.
Bruno Guimaraes made victory sure on 76 minutes.
And this time Onana's replacement was to blame.
Bayindir threaded a pass beyond his defenders to towards half-way line but it was easily intercepted – enabling Bruno Guimaraes to surge on and slip the Toon's fourth.
