Olivier Giroud's 11th goal of the season fired Arsenal back to the summit with a scrappy victory at St James' Park.
The Frenchman pounced with a 65th-minute header to seal a tight encounter which never really took off, although the Gunners were grateful when goalkeeper Wojciech Szczesny blasted a clearance straight at Loic Remy and saw the ball run just wide of the post with time running down.
Arsene Wenger's men enjoyed long periods of possession at St James' Park, but were rarely able to make it count, and it took a set-piece from Theo Walcott, who was otherwise largely anonymous, to present Giroud with his big chance.
Newcastle might have gone in ahead at the break had Szczesny not tipped over Moussa Sissoko's effort or had Mathieu Debuchy's header not come back off the crossbar.
However, they were unable to sustain the pressure as they slipped to just a second defeat in 10 league outings in front of a crowd of 52,161.
Chelsea recovered from conceding a fourth-minute opener to Martin Skrtel to beat Liverpool 2-1 at Stamford Bridge.
The Blues did the recovery work before half-time as Eden Hazard equalised before Samuel Eto'o bundled in a shot Simon Mignolet may think he could have saved.
Chelsea remained in third but ensured they finished the day still two points behind Arsenal.
Liverpool, who were top at Christmas, are now six points adrift in fifth place and behind city rivals Everton who beat Southampton 2-1.
The Toffees - looking to bounce back from the Boxing Day defeat to Sunderland that had ended their hopes of going through the whole calendar year unbeaten at Goodison Park in the league - went ahead in the ninth minute when Seamus Coleman burst into the area and finished with a powerful strike.
Saints substitute Gaston Ramirez equalised in the 71st minute, beating Toffees goalkeeper Joel Robles, who it appeared should have done better in his attempt to save the effort, with a shot from distance.
But the hosts were back in front as Romelu Lukaku converted from James McCarthy's pass, the on-loan Chelsea striker taking his tally for Everton this season to nine goals.
Tim Sherwood tasted victory at White Hart Lane for the first time as Tottenham put on a vintage display to crush Stoke 3-0.
Roberto Soldado converted his fifth penalty of the campaign while Aaron Lennon and Mousa Dembele also scored fine goals to give Spurs a comfortable 3-0 win.