Arsenal claimed a first Premier League win against Manchester United at Old Trafford since 2006 following a 1-0 victory on Sunday.
Pierre-Emerick Aubameyang was the hero for Arsenal after converting a second half penalty.
Arsenal have now won away at a “big six” side in the Premier League for the first time since a 2-0 win against Manchester City in January 2015, ending their 29-game winless run (10 draws, 19 loss).
Also, United have failed to win any of their opening four top-flight games at Old Trafford for the first time since 1972-73, a campaign in which they finished 18th.
Arsenal are now in eight position on 12 points while United are 15th on seven points.
Former Nigeria international Odion Ighalo was not included in the United squad.
The first big chance for United came in the 21st minute as Marcus Rashford picked up a pocket of space on the right wing and thread a pass out to Mason Greenwood whose one-time was stopped by by Bernd Leno.
In the 36th minute Hector Bellerin’s cross made it through to Pierre-Emerick Aubameyang who pulled it back but a slight touch from Victor Lindelof took ot away from Alexandre Lacazette.
Just three minutes later Aubameyang did a one-two with Willian on the edge of United box but the Brazilian’s left-foot strike clipped the cross bar.
Arsenal almost took the lead on 52 minutes through Aubameyang who was played on by Lacazette but his curler went just wide.
United had a chance of their own on 55 minutes from a free-kick from Luke Shaw but Harry Maguire could not direct his header toward goal.
On 58 minutes Thomas Partey tried a long range effort which was well saved by David De Gea.
Arsenal took the lead on 69 minutes through Aubameyang who scored from the penalty spot after Paul Pogba fouled Bellerin.
On 85 minutes United almost equalised but a cross from the right hit Mohamed Elneny and Leno on the face and came off the post.