Some of the travelling faithful were likely among the millions who began their day searching for tickets to see their fellow Man City supporters Noel and Liam Gallagher at next year's Oasis reunion.
The away contingent had to endure a lengthy queue to secure their spot to see Liam and co, but they did not have to wait long for their frontman to open the scoring at the London Stadium, with Haaland requiring just 10 minutes to get his name on the scoresheet.
However, less than 10 minutes later, Man City defender Ruben Dias wanted to fade away after he inadvertently diverted the ball into his own net from Jarrod Bowen's low cross.
Unfortunately for West Ham, they were level for just over 10 minutes as their backline failed to step out and stop Haaland from firing a thumping left-foot strike past Alphonse Areola.
The Hammers threatened to pull level in the opening stages of the second half, with a supersonic counterattack culminating in Mohammed Kudus rattling the frame of the goal.
Little by little the Hammers started to grow in belief and enjoy promising moments of possession, but they were soon stopped in their tracks when Man City's masterplan of feeding Haaland resulted in another hat-trick for the lethal marksman.
The West Ham backline looked back in anger as they saw Haaland beat the offside trap and race through one-on-one before he produced a composed finish to beat substitute goalkeeper Lukasz Fabianski.
Having won all three of their league matches this season, Man City have shown they are going nowhere as they make a strong start to their bid to win a fifth consecutive Premier League title.
Man City will end the day up in the sky in pole position, while the Hammers are in 13th spot after winning one and losing two of their first three matches.
WEST HAM VS. MAN CITY HIGHLIGHTS
Haaland goal vs. West Ham (10th min, West Ham 0-1 Man City)
Haaland gives Man City an early lead. The Norwegian collects Bernardo Silva's neat pass and slots the ball past the helpless Areola to get his side off to an ideal start.
Dias goal vs. Man City (19th min, West Ham 1-1 Man City)
West Ham pull level thanks to a piece of fortune. However, Dias will not be feeling very lucky as he diverts the ball into his own net in his attempt to deal with Bowen's low cross.
Haaland goal vs. West Ham (30th min, West Ham 1-2 Man City)
Man City are back in front. The Citizens work the ball to their star striker, who takes a touch and fires a left-foot strike high into the net.
Haaland goal vs. West Ham (84th min, West Ham 1-3 Man City)
Haaland makes it back-to-back hat-tricks as he times his run to race onto Matheus Nunes's through ball, before lifting his left foot shot past the helpless Fabianksi.
MAN OF THE MATCH - ERLING HAALAND
Not content with netting a hat-trick last weekend, Haaland scored another three goals to continue his and Man City's impressive start to the season.
The 24-year-old showcased how dangerous he can be with his clinical left foot, netting all three strikes that he registered on target.
The Norwegian also showed his intelligence as a forward to time his run for this third goal to perfection, with that strike representing his seventh goal in the first three matches of the new Premier League season.
WEST HAM VS. MAN CITY MATCH STATS
Possession: West Ham 32%-69% Man City
Shots: West Ham 8-22 Man City
Shots on target: West Ham 1-7 Man City
Corners: West Ham 2-11 Man City
Fouls: West Ham 10-3 Man City
BEST STATS
WHAT NEXT?
Man City will carry significant momentum into the international break, and they will look to continue their impressive start when they return to action against Brentford on September 14.
As for the visitors, they will travel to Craven Cottage for a meeting with Fulham when the Premier League resumes in a couple of weeks.