It was some transformation after Reading had looked odds on to claim a fifth successive win following a superb finish to the second half.
After falling behind to Antoine Sibierski's sixth goal in nine starts, two James Harper goals in three minutes left the Royals in charge and they could easily have had another couple before half-time.
A controversial Obafemi Martins penalty had the sides level before Turkey international Emre scored a stunning winner late in the game with a candidate for goal of the season.
Incredibly, Newcastle were jeered off at the break and cheered off at the final whistle.
It was a special day for skipper Shay Given who made his 300th Premiership start - his 298th for United to go with the couple he had at Blackburn - in this odd five-goal thriller.
An early James Milner run ended with him firing over before a Martins glancing header was grabbed by Marcus Hahnemann at the second attempt.
Sibierski, on his 100th Premiership start, then wasted a glorious 14th minute opportunity when he met a Milner right-wing cross on the penalty area but the unmarked Frenchman headed straight at the keeper.
But Sibierski made amends seven minutes later when he was presented with another headed opportunity and this time firmly put away Nolberto Solano's centre.
Newcastle were in total control and Martins should have done better when driving over and then headed another cross on to the bar.
But disaster struck twice in a three-minute spell after 37 minutes. Harper levelled it up just outside the box with a shot that deflected off Solano.
And then Harper pounced again following a horrendous blunder from Celestine Babayaro.
United should have been dead and buried as twice Ki-Hyeon Seol had easy chances. First Solano robbed him in front of goal as he was about to pull the trigger and then from the resulting corner he was denied by an acrobatic Given save.
Even when Given was beaten by substitute Glen Little, Steven Taylor popped up on the line to head clear.
Newcastle were thrown a lifeline when Ibrahima Sonko was harshly judged to have fouled Martins after 57 minutes and the striker scored his first home Premiership goal from the spot.
It was then left to Emre to grab his majestic winner. Robbing Harper on the halfway line, the little midfielder surged forward to rifle the ball over Hahnemann from 30 yards with a sensational strike.