Paul Dummett's deflected 90th-minute equaliser denied Louis van Gaal's Manchester United a morale-boosting victory as Newcastle United snatched a thrilling 3-3 draw in the Premier League on Tuesday.
Wayne Rooney completed a brace with a stunning 79th-minute goal to put United 3-2 up, after a 2-0 advantage procured by goals from himself and Jesse Lingard had been wiped out by Georginio Wijnaldum and Aleksandar Mitrovic.
But with United manager Van Gaal contemplating a win that would have gone some way to repairing the damage caused by Saturday's insipid 1-0 win over third-tier Sheffield United in the FA Cup, Dummett slammed home to prevent the visitors drawing level with fourth-place Tottenham Hotspur.
"Of course it feels like a defeat," said Van Gaal, whose side visit arch rivals Liverpool on Sunday.
"We have given it away. I have told that to my players. We could have scored six goals easily here, and we did not."
United were left two points off the Champions League places in sixth, with West Ham United moving above them, and could lose further ground after Wednesday's matches.
Newcastle inched to within a point of safety and while they remain in the relegation zone, manager Steve McClaren drew great encouragement from his side's refusal to be beaten.
"We kept fighting until the end and we have got a goal that feels like a winner," he said.
An eventful evening at St James' Park began prior to kick-off, with Newcastle presenting new signings Jonjo Shelvey and Henri Saivet to the crowd before honouring late former goalkeeper Pavel Srnicek with a minute's applause.
The former Czech Republic international, a veteran of several classic clashes between Newcastle and United in the mid-1990s, died of a heart attack aged 47 in late December.
The visitors quickly took control, with Rooney sending Rob Elliot the wrong way from the penalty spot in the ninth minute after referee Mike Dean penalised Chancel Mbemba for handball.
- Valencia at the double -
Rooney spurned a chance to inflate United's lead when he shot wide from Lingard's through-ball, but in the 38th minute he created their second goal with a delightful reverse pass that allowed Lingard to slot a shot between Elliot's legs.
Wijnaldum sounded the Newcastle revolt four minutes later, neatly volleying in his eighth goal of the season after Marouane Fellaini had headed Fabricio Coloccini's flighted pass into his path.
After United goalkeeper David de Gea had blocked from Moussa Sissoko and Lingard had curled wastefully over at the other end, Newcastle equalised in the 67th minute.
Chris Smalling was penalised for wrestling with Mitrovic at a corner and the Serbian firebrand picked himself up to tuck the resulting penalty past De Gea.
With 11 minutes to play Rooney restored United's lead, lashing a glorious first-time shot into the top-left corner from 20 yards after substitute Memphis Depay's shot cannoned into his path via Dummett.
But Welsh left-back Dummett had the final say with a rasping left-foot effort from the edge of the box that flicked off Smalling and zipped into the top-left corner.
Elsewhere, centre-back Joleon Lescott scored with a 58th-minute header as bottom club Aston Villa beat Crystal Palace 1-0 to end a club-record run of 19 league games without victory.
It also gave Villa manager Remi Garde his first win at the 11th attempt, although his side remain eight points from safety.
"We suffered so much in the previous weeks and today we are very happy," said the Frenchman. "The players showed pride and we deserved to win."
In the day's other game, Dimitri Payet netted a glorious free-kick and Enner Valencia scored twice as West Ham came from behind to win 3-1 at Bournemouth, who had gone ahead through Harry Arter.
Slaven Bilic's West Ham climb above Manchester United to fifth place, just a point off the Champions League places, while Bournemouth remain 16th.