Ainsley Maitland-Niles was sent off for Arsenal but late goals from Calum Chambers and Pierre-Emerick Aubameyang gave them all three points.
N'Golo Kante's superb solo effort proved a mere consolation for Chelsea as they lost 2-1 at home to Liverpool in the Premier League.
Ole Gunnar Solskjaer admits Marcus Rashford is likely facing a spell on the sidelines with a groin injury picked up against West Ham.
Manchester United have one win in the past five Premier League games after a loss at West Ham that Jose Mourinho said held no positives.
Aaron Cresswell's goal means David de Gea has conceded more free-kicks than any other goalkeeper since his Premier League debut.
Traces of attacking intent were all too scarce for an apprehensive Manchester United as they turned in a poor away performance at West Ham.
Goals from Andriy Yarmolenko and Aaron Cresswell earned West Ham a 2-0 win against Manchester United at the London Stadium on Sunday.
Unai Emery has made just one change to his starting XI from the side that drew with Watford last weekend for the visit of Aston Villa.
Manchester United manager Ole Gunnar Solskjaer played Jesse Lingard as a lone striker after Marcus Rashford's injury at West Ham.
Benjamin Mendy did not appear to take offence at a post from team-mate Bernardo Silva that prompted accusations of racism.
Plenty of thrilling sporting events are happening this week! For Astro Sports Pack customers, here's a handy guide on what to look out for in the next few days... (coverage is subject to change)
We round up the front and back pages across Europe, as Monday sees the transfer rumour mill crank into gear once again.
In a career that has seen him play for Germany, Chelsea and Werder Bremen, Red Star captain Marko Marin is enjoying his time in Belgrade.
The spat between Liverpool stars Mohamed Salah and Sadio Mane is over, according to the latter, who has "reconciled" with his team-mate.
After Manchester City's surprise defeat to Norwich City, Pep Guardiola insisted Manchester City's players are responsible for his status.
Sheffield United's ownership case has been settled in favour of Prince Abdullah bin Musa'ad bin Abdulaziz Al Saud.
Liverpool "should not underestimate" the impact the weather will have on Jurgen Klopp's decision to leave or stay at Anfield beyond 2022.
Manchester United have announced goalkeeper David de Gea has committed his future to the club by signing a new four-year-deal.
Chelsea's Tammy Abraham is the joint-leading scorer in the Premier League, but Frank Lampard has set no expectations for the 21-year-old.
European champions Liverpool could face one of four possible opponents, including Mexican side Monterrey, in the Club World Cup semi-finals.