London: 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.
Van Gaal -- who delighted the home crowd at one point by throwing himself to the ground to illustrate a foul on Herrera -- sent on two more young debutants in defender Tim Fosu-Mensah and midfielder James Weir.
The win was United's third in seven days after they beat Shrewsbury Town 3-0 in the FA Cup and Denmark's Midtjylland 5-1 in the Europa League and had the Old Trafford crowd for once roaring their approval in a difficult season.
"It's unbelievable," Van Gaal told Sky Sports about Rashford's four goals in four days.
"I can understand it last Thursday against Midtylland when you come in without any pressure but the second time is always more difficult and he did all the things I asked of him.
"Four goals in two matches is an average that's unusual."