Angus Young is on his back. The duck walk was too much; the beer-bottle guitar solo, a step too far. Holy mother of God, this guitarist isn't going to make it. And then, we witness the spasm; that magical moment when Young - still rockin' a school uniform at the tender age of 60 - unleashes that trademark, leg-kicking spin of his. Some man!
Sweating it out for Ireland, just how big a show do you expect from AC/DC in 2015? The answer is big. Very, very big. This is the awesome Acca Dacca we're dealing with. This, ladies and gentlemen, is the greatest rock 'n' roll display in the world; a sold-out, stadium-sized cartoon where canons fire, hell's bells ring, devil horns flicker, a giant, blow-up stripper doll comes to life and a strong-willed, geriatric team of British and Australian warriors flex their wrinkly muscles with one of the most anthemic catalogues in hard rock.
Yes, there a few changes. Sadly, the onset of dementia forced founding member and guitarist Malcom Young into retirement last year. His nephew, Stevie, is standing in tonight.
Drummer Phil Rudd has also been replaced by Chris Slade (Phil is having a, erm, teeny spot of bother with the law). Elsewhere, it's business as usual out front with the terrifying Young tearing it up like a man possessed, and singer Brian Johnson (67) howling, shrieking (in tune) and showboating like a man half his age.
The power and passion in which the lads dispense of their greatest hits (Back in Black, Highway to Hell and a fearsome Thunderstruck) is like nothing this stadium has ever witnessed. As a spectacle, the AC/DC circus is unbeatable; as a live concert, it is equal parts deafening and mesmerising.
There is the occasional bout of karaoke madness (You Shook Me...) and Young's bombastic, long-winded, set-ending solo threatens to run all the way into next week. But we're willing to look away, just this once. Ridiculous, over-the-top and always entertaining, this is AC/DC rocking harder than any other band on the planet, and they are mighty. HHHHI