Buoyed by victory five days earlier, the Championship champions, strengthened by around £100m of summer recruits, travelled to an Arsenal side missing Kai Havertz, Gabriel Jesus, Christian Norgaard and Ben White, who had Martin Odegaard and Bukayo Saka go off injured, and Eberechi Eze not signed in time to play.
By the end 15-year-old Max Dowman was running them ragged as Gabriel Martinelli watched on unused. Leeds United had only one player injured, albeit a key one in captain Ethan Ampadu.
Is this what we really want from our country's top sporting export?
There was fury from social media but it is hard to take criticism of Daniel Farke as a managerial "fraud" seriously when those same insults were being bandied about during the rocky – or even just flat – periods of matches last season en route to a 100-point title.
The proper gauge of a fanbase is those who follow the team away. There was no booing, no cries of "You're not fit to wear the shirt". The travelling support just sang along as if they had not noticed what was happening on the grass.
This is just the way it is in the Premier League, or at least its elite end.
Arsenal are reckoned to have spent £1bn during manager Mikel Arteta's six-year reign. Now they finally have a proper centre-forward and now Viktor Gyokeres has his first two goals for them after a miss which made you wonder if this was another big-money signing feted not to work, they could end the campaign as the best team in England.
TIMBER! Jurrien Timber (centre left) celebrates after scoring Arsenal's fourth goal (Image: John Walton/PA Wire)placeholder image
TIMBER! Jurrien Timber (centre left) celebrates after scoring Arsenal's fourth goal (Image: John Walton/PA Wire)
Howard Wilkinson needed just two seasons to turn Leeds from Second to First Division champions in the 1990s. Don Revie took five in the 60s, but was never out of the top four in that time.
"Hopefully in a few years we are competitive at this level," was Farke's damning comment.
There have always been and will always been elite teams in English football but never a chasm so wide to the rest. Even if Leeds wanted to match Arsenal's spending – an estimated £255m this summer – the rules would not allow it. And the English footballing aristocrats are themselves trying to bridge a gap after 22 title-free seasons.
SPOT ON: Viktor Gyokeres makes it 5-0 (Image: John Walton/PA Wire)placeholder image
SPOT ON: Viktor Gyokeres makes it 5-0 (Image: John Walton/PA Wire)
The result is hopeless mismatches like this.
"You wish for this fixture to be after the Champions League perhaps but it's their first home game of the season when everyone is fully on it on the back of an important win away at Man United and the new signing (Eze) is there before kick-off," noted Farke. "The whole stadium is buzzing."
The first 10 minutes were played almost entirely in Leeds' half, and although a blocked Noni Madueke shot and Odegaard's wide were all it amounted to, the visitors were being worn down.
The intensity of Arsenal's pressing frazzled Leeds' minds. Jayden Bogle was booked for fouling Madueke as he tried to control a hospital pass from goalkeeper Lucas Perri, who had faffed about with the ball in his six-yard box.
GIVEN A CHASING: Max Dowman (left) runs away from Gabriel Gudmundsson (Image: John Walton/PA Wire)placeholder image
GIVEN A CHASING: Max Dowman (left) runs away from Gabriel Gudmundsson (Image: John Walton/PA Wire)
In the 16th minute Gyokeres' rushed a gimme of an opportunity when Anton Stach gave up a ball he took with his back to goal after more unnecessary intricacy.
Daniel James had a shot blocked after 11 minutes but it was the 20th before Leeds broke the shackles in any meaningful way, another smothered effort for the winger leading to a corner. David Raya tipped over Pascal Struijk’s header.
That was the exception to the rule of Arsenal probing and pressuring, Leeds befuddled by their movement and wasteful under pressure.
They were not sharp enough mentally either, as when Jurrien Timber got between centre-backs Struijk and Joe Rodon to head in a 34th-minute corner.
One-nil at half-time offered a glimmer of hope, but Ampadu's deputy Ilia Gruev surrendered possession in stoppage time for Saka to double the lead with a fierce shot Perri could only wave at.
Gyokeres broke Leeds' offside trap to glide inside negligible resistance from Struijk and score, then Timber and fellow full-back Riccardo Calafiori both had time and space to convert a corner Struijk could not clear. It was Timber who did.
TOUGH EVENING: Leeds United's Pascal Struijk (right), up against Viktor Gyokeres (Image: Julian Finney/Getty Images)placeholder image
TOUGH EVENING: Leeds United's Pascal Struijk (right), up against Viktor Gyokeres (Image: Julian Finney/Getty Images)
Lukas Nmecha and Sean Longstaff were waiting to come on, but with 56 minutes gone, substitutions were no longer about the result, just squad management.
Arsenal brought on Dowman and the Premier League's second-youngest debutant after fellow substitute Ethan Nwanieri shot over, then volleyed wide before an exhausted-looking Stach clipped his ankle in the third added minute.
Gyokeres buried the penalty.
With Leeds' shortcomings largely forced by Arsenal's intensity, it was hard to be too critical of them.
After losing 5-0 to an injury-hit side, that was the saddest part of it.
Arsenal: Raya; Timber (Mosquera 63), Saliba, Gabriel, Calafiori (Lewis-Skelly 63); Zubimendi, Rice; Saka (Trossard 53), Odegaard (Nwaneri 38), Madueke (Dowman 63); Gyokeres. Unused substitutes: Martinelli, Arrizabalaga, Kiwior, Merino.
Leeds United: Perri; Bogle (Byram 83), Rodon, Struijk, Gudmundsson; Gruev, Stach, Tanaka (Longstaff 58); James (Okafor 66), Piroe (Nmecha 58), Gnonto (Aaronson 66). Unused substitutes: Bijol, Harrison, Bornauw, Darlow.
Referee: J Gillett (Merseyside).