The Gunners took a first-half lead after Alexandre Lacazette powerfully headed in Aubameyang's chipped cross — the Frenchman's 50th goal in all competitions for the club — before West Ham levelled through Michail Antonio on the stroke of half-time, after a devastating counter-attack.
The Hammers dominated the second period, hitting the bar through Antonio and wasting numerous goalscoring opportunities before Arsenal clinched all three points with five minutes to go as Spaniard Dani Ceballos squared the ball for Eddie Nketiah to tap in the winner.
The Gunners were controversially denied an opener with Alexandre Lacazette's fourth-minute header, as VAR (Video Assistant Referee) adjudged Granit Xhaka to have been offside in the build-up to the goal, despite not having clearly interfered with the play.
[24] A number of fringe players, including debuting goalkeeper Rúnar Alex Rúnarsson, played as the Gunners continued their perfect Europa League start by cruising past Irish side Dundalk 3–0.
[31] Mohamed Elneny and Sead Kolašinac both tested positive for COVID-19 on international duty for Egypt and Bosnia and Herzegovina respectively, and a thigh injury to Thomas Partey against Villa left the Gunners weakened upon their trip to Elland Road to face Leeds United.
After Nicolas Pépé hit the crossbar with a fine curling effort on 48 minutes, the Ivorian atoned for his red card at Elland Road by firing in Joe Willock's overhit cross, before an Eddie Nketiah goal was ruled out for offside.
He received the ball from fellow substitute and academy graduate Emile Smith Rowe and swivelled before beating goalkeeper Andreas Linde from close range to wrap up a comfortable 3–0 win and book their places in the knockout stages with two games to go.
A Rob Holding own goal and a Yerry Mina header on either side of Nicolas Pépé's converted penalty before half-time gave the Toffees the win, with David Luiz coming closest for Arsenal in the second half when he hit the post with a well-struck half-volley.
A snowstorm before and during the game made for less-than-ideal conditions, but Arsenal were on the front foot from the start, and a cross from Bukayo Saka to the back post proved to be just too far for captain Pierre-Emerick Aubameyang in the fifteenth minute.
Smith Rowe was able to redeem himself early in the second half of extra time as he chested down a pass from Alexandre Lacazette before firing a shot from a tight angle across the goal and off the near post to put Arsenal ahead.
On the other hand, Arsenal struggled to seriously trouble Crystal Palace goalkeeper Vicente Guaita, and arguably their best performer was Granit Xhaka, who put in key tackles to stop Wilfried Zaha on several counterattacks.
An own goal from Gabriel, who deflected a shot by Southampton right-back Kyle Walker-Peters past Bernd Leno, proved to be the difference, handing the Saints a 1–0 win and ending the Gunners' six-match unbeaten streak in all competitions.
Less than a minute later, with Arsenal still on the attack, Cédric hit a looping cross into the box that met the head of Victor Lindelöf and fell to an unmarked Emile Smith Rowe, whose low shot towards the bottom corner forced de Gea to get down quickly and parry it away.
Gareth Bale played a switch ball across the field to Sergio Reguilón, whose first touch pass fell to Lucas Moura in the box, who in turn tapped it to substitute Erik Lamela, on for the injured Son Heung-min.
The Gunners hoped to rebound quickly; a pacy first-time cross from Kieran Tierney fizzed across the box to Nicolas Pépé, but his shot deflected off the head of teammate Emile Smith Rowe and over the bar.
West Ham dominated possession in the opening fifteen minutes, and their efforts paid off when Michail Antonio found Jesse Lingard on the edge of the box, whose shot curled away from Bernd Leno into the top far corner.
Martin Ødegaard played it out wide for Chambers to hit a first time cross into the box, but instead of it reaching an Arsenal player, West Ham center-back Craig Dawson's forward momentum saw him smash the ball into the back of the net before he collided into Fabiański.
Trent Alexander-Arnold's cross found substitute Diogo Jota in between Calum Chambers and Rob Holding, and the Portuguese forward's header from close range was too powerful for Bernd Leno to keep out.
[98][99] In the second leg of the Europa League quarter-finals on 15 April, Arsenal hoped to finish the job against Slavia Prague and advance to the semi-finals, and a three-goal flurry in a six-minute span early in the first half essentially wrapped up the tie.
Shortly thereafter, the first goal would come in the eighteenth minute; Smith Rowe wriggled around several Slavia Prague defenders in the box and slipped a pass through to Nicolas Pépé, who bided his time before finding a better angle to fire past Ondřej Kolář from close range.
For the foul, referee Cüneyt Çakır showed Hromada a yellow card and awarded Arsenal a penalty, which Alexandre Lacazette successfully converted into the opposite corner by hesitating briefly to send Kolář diving the wrong way.
[101][102] Despite blitzing Slavia Prague for four goals midweek and beating Fulham comfortably in Matchweek 1 of the season, Arsenal came crashing back down at home on 18 April against the 18th place Cottagers, with neither side seemingly able to fire on all cylinders.
[109] Although Arsenal hoped to return to winning ways after the underwhelming draw against Fulham, their disappointing Premier League form continued on 23 April, as they lost at home to Everton 1–0 thanks to a Bernd Leno own goal late in the game.
At the half-hour mark, Bernd Leno did enough to parry a Richarlison shot out of the reach of a fast-closing Dominic Calvert-Lewin, while Gylfi Sigurðsson hit the top of the crossbar with a free kick from around 27 yards out in the thirty-ninth minute.
To make matters worse for Newcastle, a poor tackle from Fabian Schär on Martinelli in the ninetieth minute resulted in a straight red card and a dismissal from referee Mike Dean, capping off a comfortable 2–0 Gunners win.
Twenty-nine minutes in, Willian played the ball down the line for Bukayo Saka, whose low cross found Emile Smith Rowe amongst the West Brom defense to be volleyed in from close range for the latter's first Premier League goal in 19 appearances.
Mason Mount's corner in the sixty-first minute was headed onwards by Havertz to the back post for Christian Pulisic, who made a darting run behind the Arsenal defense, to redirect into the net with his chest from close range.
The first half hour saw barely any threatening shots from either side until the thirty-second minute, when Christian Benteke headed the ball down for Jeffrey Schlupp to try a volley from just outside the box, which forced Bernd Leno to make a diving fingertip save to his left.
A few minutes later, after several passes down the left flank between Bukayo Saka and Kieran Tierney, the latter sent in a cross that found Nicolas Pépé, who made a late run into the box to volley the ball in and give Arsenal the lead.
Heading into the match, Arsenal needed to win against Brighton and have seventh-placed Tottenham Hotspur and eighth placed Everton, who were both a point ahead, draw or lose in order to leapfrog them into seventh and qualify the newly formed UEFA Europa Conference League.