Teenager Marcus Rashford followed up two goals on his Manchester United debut in midweek with another double plus an assist as Louis van Gaal's team dented Arsenal's Premier League title hopes with a 3-2 win on Sunday.
The result left third-placed Arsenal five points behind leaders Leicester City while United returned to fifth place above West Ham.
The 18-year-old Rashford struck twice in three minutes in the first half before former United striker Danny Welbeck pulled one goal back for Arsenal. Rashford then set up Ander Herrera for United's third before Mesut Ozil reduced the deficit.
With a dozen senior players unavailable, including captain Wayne Rooney, the under-pressure Van Gaal gave a first league appearance to Rashford, who responded brilliantly.
After 29 minutes he was in the right place to capitalise as Arsenal defender Gabriel could only half-clear Guillermo Varela's right-wing cross.
Three minutes later he headed United's second goal as Jesse Lingard was given too much space to cross from the same area.
Arsenal, needing a win to keep pace with local rivals Tottenham as challengers to Leicester, were given some hope before half-time when Welbeck -- who once played for the same Manchester boys' club that produced Rashford -- glanced in Ozil's free kick.
It was the German's 18th assist of the season and he added a goal of his own in the second half but not until Rashford kept possession and his head before passing square to Herrera, whose 20-metre shot was deflected in off Arsenal defender Laurent Koscielny.
Tottenham close gap at top by beating Swansea
Tottenham Hotspur came from behind to achieve a crucial 2-1 home win over lowly Swansea City in the Premier League at White Hart Lane.
Italian striker Alberto Paloschi, signed from Chievo in the January transfer window, scored his first goal for the Welsh club to give them a half-time lead.
Substitute Nacer Chadli equalised with 20 minutes left and full-back Danny Rose scored the winner seven minutes later.
Seeking a first league title since 1961, second-placed Spurs are now two points behind surprise leaders Leicester City with 11 games to play.
It was their sixth successive Premier League victory since they lost at home to Leicester in January, although for a long time Swansea's former Arsenal goalkeeper Lukasz Fabianski seemed likely to deny them at least two points if not three.
He made fine saves from Harry Kane, who was playing in a mask to protect his broken nose, Christian Eriksen, who threatened more than once from free kicks, and Eric Dier.
Paloschi, who cost Swansea a reported eight million pounds($11.10 million), scored after 19 minutes when Angel Rangel's shot fell nicely for him in the penalty area.
There were 20 minutes left when Belgian international Chadli turned in Kyle Walker's shot. Then left back Rose became the hero of the day by beating Fabianksi when a corner was headed out to him.
Hugo Lloris kept out a volley by Paloschi for an invaluable win, made even better by defeat for third-placed local rivals Arsenal, who have slipped three points behind them.
Spurs play at home to Arsenal on Saturday after another big London derby away to West Ham on Wednesday.
"It was hard because from the beginning we conceded chances and Swansea scored," manager Mauricio Pochettino said.
"You play well but find it hard to score. The good thing is that the team fight. It is a fantastic win. Fabianski was great. He was man of the match."
