Bruno Fernandes struck in stoppage time to settle a tight encounter of few chances in what was the Dutchman's 79th match in charge of United.
This is the joint-quickest it has taken any manager to rack up a half century of victories for the Reds, with Ten Hag equalling a landmark which, incredibly, has stood for 118 years.
Ernest Mangnall, who led the club to its first major trophy in winning the 1908 First Division title, also registered 50 wins in his first 79 games, crossing the milestone in 1905 when United beat Blackpool 1-0 at Bloomfield Road.