Anthony Martial and Paul Pogba kick-started the New Year's Eve celebrations for Manchester United with late strikes as Jose Mourinho's men saw off a spirited Middlesbrough 2-1 at Old Trafford.
United were well worth a victory that they looked to have been denied for long parts of the game by poor refereeing, dogged Middlesbrough defending and Grant Leadbitter's goal.
However, Mourinho eventually came out on top in the battle with his former Real Madrid assistant Aitor Karanka with a late comeback straight out of the playbook of Sir Alex Ferguson, celebrating his 75th birthday in the stands.
Mourinho may well have been readying himself for a post-match whinge after referee Lee Mason controversially denied Zlatan Ibrahimovic a first-half goal before Leadbitter put Boro ahead on his first start of the season.
However, Martial's finish and Pogba's header arrived within two minutes of each other to spark a frenzied atmosphere and move United a point behind Arsenal.
Boro were left to rue having just a second away win of the season cruelly snatched away from them, with a home fixture against champions Leicester City providing little respite for a side now just two places above the bottom three.
Adama Traore wasted a gilt-edged chance in the third minute for the visitors, shooting woefully wide after leading a three-on-one counter-attack.
Pogba hit the post with an overhead kick as United responded, but Traore remained a fleet-footed pest on Boro's right, zipping past Daley Blind and Chris Smalling before George Friend's resulting shot was blocked after he had passed on an open-goal opportunity first time.
At the other end, Martial was similarly menacing and dribbled through a clutch of defenders to tee up Henrikh Mkhitaryan but Victor Valdes was equal to the shot.
There was controversy seven minutes from the break, however, as Martial smashed the left-hand post from 30 yards before recovering possession and crossing for Ibrahimovic to acrobatically finish, only for Mason to harshly adjudge the Swede - at least two yards away from Valdes - guilty of dangerous play.
Former United keeper Valdes immediately became the villain of the piece for the home faithful and he saved sharply from Ibrahimovic early in the second half too.
Blind had to be substituted after picking up a booking for scything down Traore, with Juan Mata also replacing Marouane Fellaini, but the change backfired on Mourinho as Boro snatched the lead.
Alvaro Negredo had ploughed a lonely furrow up front, but his quality shone through to nod a Calum Chambers cross down for Leadbitter to drill home and send the travelling support wild.
Marcus Rashford was summoned from the bench and ought to have had a penalty when he was fouled by league debutant Bernardo Espinosa, but any Mourinho invective was quickly tempered by a thrilling finish.
Martial spurned a chance when one-on-one but the France international got a goal that could kick-start his season soon after, latching onto Ibrahimovic's flick and steering in at the near post.
Boro had barely a chance to reorganise when they were behind.
Pogba stole in at the near post to steer home Mata's right-wing cross and completed a vintage United turnaround that sets them up for a second-half season surge.
