Mikel Arteta's side looked to have missed the chance for a first Premier League title in 22 years again when they lost at City in mid-April; however, an uncharacteristic slip-up against Everton from Pep Guardiola's team meant that the Gunners' destiny would be back in their own hands.
Arsenal on the front foot
A loss against Brentford last time out for the Hammers, coupled with a Tottenham win at Aston Villa, meant that the East Londoners began this game in the relegation places, and a point adrift of safety.
Therefore, the result would affect both the very top and bottom of the table.
Nuno Espirito Santo could take heart in the fact that his side were on a six-match unbeaten run at the London Stadium, and had lost just two out of their last six games, the same as their visitors.
Arguably, the standard of West Ham's performance could be secondary to them earning all three points, and heaping the pressure back on Spurs before they took on Leeds on Monday night.
Far from sitting back and easing themselves into the match, Arsenal were on the front foot from the very first whistle, and had already had seven attempts at goal in the opening 15 minutes, including from Leandro Trossard, one of which was magnificently saved by Mads Hermansen, and a follow-up which hit the woodwork.
Summerville making a nuisance of himself
The Irons were left chasing shadows for long periods, as the Gunners dominated that period of the game with 68% collective possession.
Not long afterwards, Riccardo Calafiori saw his third effort cleared off the line, and only Axel Disasi out of the entire Hammers back line managed a single successful tackle during Arsenal's attacking barrage.
In fact, it remained the only successful tackle from the hosts' back four during the entire afternoon, though Konstantinos Mavropanos was working overtime in terms of clearances, and had already come to his colleagues' rescue on several occasions.
It wasn't until the 35th minute that West Ham even managed anything approaching an effort at goal, and even then, Crysencio Summerville wasn't able to get it on target.
The former Leeds United man was at least trying his best to make a nuisance of himself and was booked shortly after for a reckless foul.
Raya keeps Arsenal in it
By the end of the game, he'd won nine of his 15 one-on-one duels, had won back possession on three separate occasions, and had also completed three of his five dribbles successfully.
Taty Castellanos' magnificent diving header was West Ham's only effort on target in the first half, and that was due in no small part to Arsenal's silky movement around the pitch and their accuracy in their passing.
David Raya's flying one-handed save to deny the striker wouldn't be the only time he'd be called upon to keep his side in the match, either.
Whilst the hosts were struggling to get anyone on the ball for a decent period of time, Eberechi Eze was strolling around the London Stadium completing 97.3% of his passes, and was only topped by William Saliba's 98.8%.
Half-time brings respite for the Hammers
Indeed, the way in which the North Londoners were often toying with their hosts was a masterclass in how to wear the opposition down.
Declan Rice was again prominent against his old club, driving Arsenal forward when they needed to be higher up the pitch, and delivering the ball into the danger areas on no fewer than 10 separate occasions.
The half-time whistle at least gave West Ham some respite, and two chances right at the beginning of the second half will have given the supporters hope.
However, the Gunners were still going for the jugular, and collective possession had risen to an astonshing 79% by the hour mark.
Trossard strikes late on
Despite this, the visitors were finding it difficult to get the best out of their top scorer, Viktor Gyokeres, and just two touches in the Hammers' box didn't lead to a shot on target for the bullish frontman.
Bukayo Saka was strangely off colour too, completing none of his five dribbles successfully, or winning any of his 10 one-on-one duels.
Raya was again called upon late on as a swift West Ham move saw Matheus Fernandes bear down on the Spaniard, though it was the custodian who stuck out a leg to divert the ball from danger, one of three important saves that he made on the day.
It proved to be vital too, as just five minutes later, Trossard's venomous strike found the bottom corner and sent anyone connected with the Gunners delirious. It was the Belgian's fifth goal in 13 appearances against the East Londoners, and was immediately obvious to all just how much the goal meant to both sides.
VAR controversy
Arsenal hadn't lost away when scoring first this season, and West Ham hadn't won in nine when conceding first, so the writing was very much on the wall at that point for the hosts.
However, just 10 minutes after coming on as a late substitute, Callum Wilson looked to have salvaged a point during injury time, and dented the North Londoners' title aspirations in the process.
After an extensive VAR check, however, the goal was, perhaps controversially, ruled out, meaning that Arsenal had earned an 18th clean sheet in their 36 games, more than any other team in the top flight.
West Ham will rue such a decision, of course, but the fact is they only managed three attempts on target all game, and arguably didn't do enough to earn themselves a point, which would've gone some way to giving them hope of avoiding the drop.
