“We're Clutch, professional musicians...we need a new cable endorsement!” declares frontman Neil Fallon as the band arrive on the Zippo Encore stage with a slight technical hitch.
So slight is it that we're ushered straight into Your Love is Incarceration (taken from 2015's Psychic Warfare) and from there on in Maryland's quartet rock out with a 40 minute set (Just 40 minutes!) that encourages much head-nodding and general good feeling.
Clutch have been a work in progress since 1991 and that means there is a whole heap of Clutch class ready to be heaped onto those who have turned up at the so-called second stage.
They thrill with Mob Goes Wild, X-Ray Visions, Firebirds!, Decapitation Blues and Burning Beard before teasing us with a new track.
“You can play guinea pigs,” Fallon says before bursting into a roar-some political piece about being President...
Sucker For the Witch follows in a set pulling heavily from their Psychic Warfare opus, but they appease the die-hards, unleashing Escape From The Prison Planet.
D.C Sound Attack finds its way into the setlist too, and Clutch are all bristling and brilliant, with Fallon adopting his now familiar preacher-like stance as he spills out his clever lyricisms.
The last time Clutch hit Download a couple of years back, they made their main stage debut to raptuous response, so this Stage 2 billing is a little bewildering.
It's a blinding 40 minutes that speeds by way too quickly, and sees the earth rockers at their smokin' best.
Back on the main stage - and following a typically cheeky, glam-o-rama set from Steel Panther who seem to have commandeered half the DL female of the species during their set, Alter Bridge are back.
Myles Kennedy has one of hard rock's most distinctive, and impressive voices, and when he cuts it loose on modern classic Isolation, it's perfect.
Which is just as well because there's no time to wait - we've got business to attend to elsewhere in the field...
It's like snuggling into that old trusty denim jacket from decades ago - the one with the South of Heaven patch on the back, held together more by dirt than by thread. It's comfortable.
That's how Slayer's headliner appearance on the Zippo Encore stage feels today.
But that's not meant in the least bit derogatory, because Slayer put in one of the performances of the weekend, with a pile of perfectly plump thrash classics which tumble out with the usual full-on ferocity that few can match but plenty try to imitate. It's just so nice to hear them in the live again.
Can we call them the Godfather's of the genre? After all they have been firing out the metal for more than 35 years.
That's mental, but not as much as the reception Slayer command when they stroll out onto the stage in the evening sun.
Not 'very Slayer' weather, is it?!
The band are fiery and fabulous, and watching guitarists Gary Holt and Kerry King playing with resolute conviction, either side of an ever-cool Tom Araya is a definite delight.
When we say 'watching' though, we really mean craning to see, because with an enthusiastic amount of smoke being released on stage, and that sun glistening down, frankly, it's a bit of a bugger to see anything at times.
From our vantage point we can't see over the crowd, but something tickles the security guards stage front, and whatever it is, catches the eye of Tom too, who laughs his way through part of Mandatory Suicide. We're not talking a bit of a wry smile, but a proper giggle.
The audience on the whole aren't laughing, but they are beaming wildly by the time Slayer sign off today, having also smuggled Dead Skin Mask, South of Heaven and Angel of Death into their set.
Nobody does it better.
There's a hum in the Donington Park air tonight, and it comes on long before the Toxic Twins come to play with us - although the hum is connected; 80,000 people are enjoying the unfashionable warm weather (so, it was a little fresh, but we can live with that) and awaiting the last UK performance by Aerosmith.
Can it really be so?
There's no time to get teary-eyed though, as the behemoths of rock n roll have a setlist and a half to work through, and it's straight to business with Let The Music Do The Talking, which both sets the tone and explains how the nexttwo hours is going to roll.
Young Lust, Love In An Elevator, Janie's Got a Gun, Don't Wanna Miss A Thing, Rag Doll...it's a masterclass in the art of songwriting.
It's an all-generational thing too - those that have seen it all before nod in time, knowingly, teenagers roll around screaming the lyrics and miniature dance parties are breaking out all over the site.
No-one moves with the energy of the man at the mic though, and Steven Tyler is a swirl of black and pink material and motion and absolute rock star status.
This is the real deal, and when he sidles up to guitarist Joe Perry, it's perfection. The wind carries the occasional vocal away a from its bullseye, but that's ok.
We know what Aerosmith are about, and they ain't about to change at this stage of the game.
Steven's daughter, actress Liv Tyler is watching in the wings as her dad works a field full of 80,000 punters as easily as his country's President effs things up.
Tyler is a rockin', playin' juggernaut who breathes a little fire into The Beatles' Come Together to continued audience delight.
Eventually Walk This Way is chosen to bring the curtain down not only on a stellar year of delicious Download action, but also on Aerosmith so far as the UK is concerned.
If that really is the last we'll see of Boston's blues-rockin' Kings, things will never be quite the same...
