However, debutant goalkeeper Martin Dubravka was brilliant in goal for the home side, including making a stoppage time save to keep a clean sheet and earn the three points for his side.
In the other game Sunday, Huddersfield collected its first league win in almost two months by beating Bournemouth 4-1 to climb out of the relegation zone.
Newcastle then made the visitors pay for their profligacy, as a Shelvey free-kick was pumped into the box and flicked back to the unmarked Ritchie, who drove the ball past a diving De Gea. In a similar way, the Newcastle players fought for 90 minutes.
The second half saw United have the ball in the back of the net through Lukaku within seven minutes, only for it to be chalked off for a push by Smalling in the build up, and one from Lukaku himself.
It proved a costly miss.
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His speech (viewable below) attracted major media attention in the United States, with ESPN's hugely popular Sportscenter program labelling it an "epic rant".
"A defender has to concede free-kicks now and again".
A 2-0 victory over Huddersfield last week, in which new signing Alexis Sanchez was outstanding, helped United make minor inroads into Manchester City's colossal lead, although the gap was still 13 points going into this weekend's fixtures.
Jose Mourinho's side were the overwhelming favourites heading into the Premier League game at St. James' Park, but it was the home side who picked up all three points from the encounter.
The France global has scored three times and set up a further nine in 16 Premier League appearances this season as United look to challenge Manchester City to the title, but faced criticism for his performance in a recent 2-0 defeat to Tottenham Hotspur.
Matt Ritchie ended a run of 43 shots this season without scoring in the Premier League, which was the longest such run in the division.
Newcastle always remained a threat at the other end and after the Magpies were awarded a free kick on the halfway line due to simulation from Smalling, they went in front.