With West Ham out of form, and Arsenal unbeaten domestically prior to this fixture, the Gunners would have been hopeful of ensuring their progression into the next round of the competition.
This hope would quickly prove to be to their detriment, as they lost control of the game from an early juncture, and went behind via a Ben White own goal.
The hosts' onslaught continued into the second half as they doubled their lead shortly after the break, before adding a third just a short while later thanks to Mohammed Kudus and Jarrod Bowen respectively.
A late consolation goal for the visitors through captain Martin Ødegaard proved futile, as the referee brought proceedings to an end just moments later.
It was a frustrating evening for the visitors, who bowed out of the competition at a much earlier stage than they would have hoped for.
It was jubilation for the Hammers, however, as they overturned their recent form and secured their places in the draw for the quarterfinals - where they will face a trip away to Liverpool.
Here are VAVEL's takeaways as David Moyes' team outclassed a strong Arsenal side.
-
Form is temporary, class is permanent
It would have been very easy for West Ham's recent form to cloud their mind as they came up against a side who were previously unbeaten domestically.
This was not the case though and they showed sheer dominance against a team that they were expected to struggle against.
Not only were they very impressive to take the lead, but their ability to keep pushing even when they were two goals to the good showed an incredible mentality - which was more than matched by their performance on the pitch.
It proves that the quality of a team is not necessarily defined by their most recent results. While tough times will no doubt occur, they have shown that they are no flash in the pan and, in years to come, will still very much be able to compete with the 'big boys' of English, and possibly even European, football.
-
Mounting injuries a problem for Arteta
Injuries are part and parcel of football and, as the intensity of the game and its schedule increases, are only going to become more common. This can never be an overarching excuse for poor form, but it can certainly be an overwhelming factor.
Arsenal now have somewhat of an injury crisis, and it is becoming increasingly evident, and problematic, as time passes.
Gabriel Jesus, Jurriën Timber, Thomas Partey and Emile Smith-Rowe are all currently sidelined for the Gunners, and at least three of those players would probably appear in Arsenal's 'strongest' line-up.
While the North Londoners have found an increased level of depth over the last year or so, having this many injuries to key players is bound to have an impact on their performances.
Not only does the actual level of the players drop, but so too does the team's cohesion, which is a difficult obstacle to overcome for any manager.
Only time will tell how big an impact these, and any further, injuries could have on their season, but it is clear, and perhaps stating the obvious, that they are a far weaker side as a result of them.
-
West Ham have a genuine shot at more silverware
Without trying to belittle West Ham who have, after all, won two major European trophies, winning silverware is not exactly a regular occurrence for the East London outfit.
So if you told Hammers fans that they would win the UEFA Europa Conference League, and then back it up the following season by winning a domestic trophy, many would have probably laughed at you not so long ago.
But, now, those same fans might even be expecting such an outcome - given the great position that they find themselves in. Liverpool, Newcastle and Chelsea are the toughest sides left in the Carabao Cup this season, with the two latter sides drawn against each other in the next round, while Moyes and his team face Liverpool.
Winning at Anfield is no easy feat but, if they manage to do so, only one team, on paper, should stand in the Hammers' way of another trophy.
In beating Arsenal they have already shown an ability to dismantle top sides, though they will now need to do so without home comforts. That being said, it could still represent their best, and a very viable, route to back-to-back silverware, which is nothing to turn your nose up at.
-
Arsenal's goalkeeping situation is unsustainable
Many people raised their eyebrows when Arsenal signed David Raya on loan from Brentford in the summer, with Aaron Ramsdale having just signed a new deal to secure his future at The Emirates.
Ramsdale initially kept his place but, after a few games, Raya was handed a start and has retained the starting spot ever since, except for the occasional cup game.
Little would have likely been said if the Spanish shot-stopper had come in and been an immediate upgrade on the previous number one, but this has not necessarily been the case.
Raya has looked shaky in goal at times and has been at fault for a number of goals that the Gunners have conceded so far this season. Not only this, but the few appearances that Ramsdale has made since have highlighted a lack of confidence, which has caused some more nervy moments in goal.
It feels like a dynamic that is never going to see either goalkeeper thrive, especially given the pressure while the other watches on from the dugout, waiting for a mistake.
Mikel Arteta needs to get a grip on this situation very quickly to gain some stability between the posts, which would go a long way to help them defensively. What is the answer? Only time will tell, signing Raya was always a risk and now the manager needs to make it work for all parties - and quickly.
