They went into the holiday period with a ten-point advantage and, although they were unbeaten over their two-match campaign, that gap has now been slashed to six points following disappointing draws with struggling Sheffield Wednesday and Derby County.
With West Brom reaping maximum points, the goalless clash with Derby was ill-timed to say the least especially as the Rams ended with ten men after full-back James McEveley was sent off in stoppage time for two bookable offences.
Twice United hit the woodwork, but it was one of those days they never looked like scoring, although they had plenty of chances against a Derby side that was able to end a run of three successive defeats.
It was the lowest Championship away scorers against the meanest defence, with United having conceded just four goals at home as they went in search of a sixth successive home win.
Newcastle stretched their unbeaten home run to 12 games but this was a great point for Derby who became only the third team to take anything away from St James' Park this season.
The result made it 11 games since United last tasted Championship defeat after Chris Hughton made four changes to the side held 2-2 at lowly Wednesday on Boxing Day.
United were close to making a dream start when Peter Lovenkrands broke clear on the left after just two minutes and hung up a teasing cross that Andy Carroll headed the wrong side of the post.
The early pressure was all from Newcastle and, when Lovenkrands was fouled on the edge of the area, Ryan Taylor took over free-kick responsibilities and saw his effort smash against the bar with Stephen Bywater only able to watch.
Carroll then headed another left-wing cross wide with Jose Enrique supplying the centre before another raid down the left flank saw good footwork from Lovenkrands but his effort flashed just wide.
Ryan Taylor then sprung the offside trap to meet a Jonas Gutierrez throughball only to see the outstretched leg of Bywater force the ball behind though the midfielder should have done better.
It was not until the 25th minute that Derby sprung to life as an attacking force, Steve Harper making an excellent reflex save to deny Dudley Campbell following good work from Stephen Pearson.
United's wastefulness in front of goal was highlighted again after 57 minutes when Carroll stood the ball up perfectly for Steven Taylor who was unmarked on the penalty spot only for the defender to head straight at a relieved Bywater.
The inspirational Bywater then came to the rescue three minutes from time with a brilliant save from substitute Nile Ranger that he turned to safety off the woodwork.