Eddie Howe's Magpies are now third in the Premier League following Sunday's 4-1 win at Southampton.
Miguel Almirón's eighth goal of the season gave Newcastle a first-half lead before quickfire goals after the break from substitute Chris Wood and Joe Willock put United in a commanding position.
Romain Perraud pulled one back for the hosts late on, but Bruno Guimarães responded almost immediately with a fourth for the Magpies, who were backed by 3,200 travelling supporters.
Their spirits weren't dampened by regular downpours on the South Coast, and there was no raining on the parade of club photographer Serena Taylor, who brought nufc.co.uk this gallery from St. Mary's.