Many of those present had left the West Auckland streets around the venue littered with liquor bottles from concert pre-loading.
And as Malone opened with his Lil Peep dedication Too Young - hook: "I don't wanna die too young" - some were already showing signs of being worse for wear.
"My parents have split up," slurred one young lad to security guards outside as Malone took the stage. He didn't make it back in.
Those that did got messy, and were treated to a mess of a show.
This was the last night of a world tour in support of last year's Stoney album, one that turned the underground cult concern into a bonafide chart sensation, and the strain was starting to show.
At one point, the 22-year-old poured beer into a punter's shoe, sculled it back, then declared, "Those are some stinky ass feet, bro," for a ritual dubbed "the shoey".
At another, he hit his microphone into his forehead, hurled it onto the stage, grabbed the guitar he'd been playing just moments before, and smashed it to pieces.
I Fall Apart? It's unlikely that guitar will be played in the same way again.
Then there was Malone's voice. On record, it's a soothing country-tinged hook machine, one that's positioned him as the Ed Sheeran of hip-hop.
But last night it turned into a throaty nicotine-lubricated croak that often failed to be heard over Malone's backing track. Add in all those long delays to sort out crowd troubles, and the recipe for a great show had gone awry.
By the time Rockstar came around, Malone sounded hoarse and looked spent, all that time on the road sculling beers out of shoes seemingly taking its toll.
There's no doubting Malone's capacity to craft hooks perfect for draping an arm around your best mate, shouting out the lyrics and holding your drink high in the air.
Or drinks. One punter shoved an entire tray of Jack Daniels and Coke cans skywards to cheers the inclusion of Malone's early hit White Iverson in the setlist.
The show did deliver moments like that, from Candy Paint's upbeat bounce to Go Flex's slow-mo stomp and I Fall Apart's soaring heartache.
There isn't a hip-hop artist working right now that wouldn't kill to be able to walk off stage after performing a swagger anthem like Congratulations.
But they were celebrated on the strength of Malone's song craft, not his performance.
Malone really needed to prove why, in less than 12 months, he's ascended to become one of the biggest voices in hip-hop.
After that shambles, it's unlikely anyone is any wiser. But by all means, pass him another "shoey," because he sure is loving that rock star life.
Who: Post Malone
Where: Trusts Arena, Auckland
When: Monday, January 15
