The booming punches of a champion, a boisterous crowd and a challenger trying to roar himself to one of the biggest upsets boxing could ever see; and this was all just at the public work-out for Gennady Golovkin v Kell Brook.
A muggy lunchtime saw hundreds of fans and curious passers-by cram Covent Garden and they were soon watching Conor Benn, John Riel Casimero, Charlie Edwards and Lee Haskins put through their paces in the ring, one after the other.
Then, with all of them departed and all other media obligations fulfilled, a sudden purposeful surge from bouncers and the collective turning of countless heads heralded the arrival of Golovkin.
It's the serenity of the man that strikes you first. The smile is boyish and the general demeanour not dissimilar to a foreign exchange student enthusiastically devouring the bustle of central London.
Depending on who you are, after a few drinks you might be dismissive of Golovkin's threat if you bumped into him in public and didn't know who he was. There also might be more than one burly miner from Karagandy with a cautionary tale about underestimating him.
Through the stretching, the skipping and the shadow-boxing, he seems to evolve stealthily into a war machine. The smile often returns; there were plenty of giggles with his long-time trainer Abel Sanchez during their routine, but the sound of him catching a pad cleanly is something gravely serious.
One particularly deafening left hook brought a 'whoop' from the neutrals in the crowd. Brook fans may have been wincing as they reached for ear-plugs. Then came that trademark shot of the Kazakh's; a hook thrown with his arm appearing to corkscrew. It's the shot he can throw from above out of nowhere. The smile returned again.
It seemed ominous, but then in bounded Brook looking full of face and strong of arm. Aesthetics belie Golovkin's violence so it's important not to make too much of Brook's, but he's always had impressively thick-set legs and he will need them if he's to withstand any of the champion's more committed work.
Still, the IBF welterweight king was beaming himself as he first saluted the crowd. For sharpness, if not for power and intrigue, his pad work-out with Dominic Ingle was cleaner than Golovkin's. Some of that may be down to Ingle's superior fitness and accuracy with the targets, but Brook's combinations looked fluent.
Then came the moment of the day. With Brook's work-out climaxing in lengthier combinations, there came loud encouragement from a group close to the front of the crowd. Brook, sensing his moment, pounced atop the turnbuckle and returned the roar with added expletives. The cheer of the day echoed back at him and any doubts whether the capital would support Sheffield's 'Special One' in his quest were dispelled.
Was Brook looking inwardly or outwardly? Trying to rouse himself into believing or trying to ensure the great British public embark on a journey he feels is destined for the most unlikely glory? If he does indeed have any private misgivings about how deep he is in, he's wearing them in style.
To the neutral, it should matter little because this fight should yield a spectacle regardless. It could be a brutal statement that cements Golovkin's reputation of the world's pound-for-pound supremo. It could be the greatest upset in the history of the sport. It could be anything in between.
Today, Brook welcomed the sight of the mountain before him for the umpteenth time, and the sound of that Golovkin left hook hitting the pad may still have been reverberating around the stone of Covent Garden.
There's already a sense of watching something special and nobody can yet be sure exactly why.
Watch Gennady Golovkin v Kell Brook, live on Sky Sports Box Office from The O2, on September 10. Book the event via your Sky remote or online here.