But System proved to be in the form of the lives at a sold out Trusts Stadium, barely pausing for breath as they ripped through nearly 30 songs during an intense 100-minute show in front of what felt like a hometown crowd.
Like other 90s acts on the comeback trail, System - who spent three years on hiatus before regrouping in 2009 - aren't playing new material, instead cherry-picking hits from across their five albums.
Fans knew every word, from the opening sludge metal flurry of Prison Song, to Psycho's barked chorus and Tankian's furiously fast spitting over the military stomp of Revenga. Try doing that when you've had a few beers.
Not many metal acts can get away with mixing up so many styles, like the ridiculous pop chorus of BYOB ("Everybody's going to the party, have a real good time"), or the salsa breakdown in Radio/Video and the lounge room balladeering in Hypnotize.
But it all comes backed by some of the best thrash-metal riffage around. Tracks from their aggressive breakthrough album, 2001's Toxicity, turned Trusts Stadium into a giant trampoline and human sweatbox, like a frenetic Needles, the soaring Deer Dance, Bounce's perfectly-timed grooves and supercharged highlight Chop Suey!
That song saw a group of girls on the Trusts Stadium balcony perform coordinated dance moves, rubbing their eyes and cutting their throats in time with Tankian's lyrics.
It was that kind of show, with strangers hugging, moshing and high fiving each other over their favourite songs.
As set highlight Aerials kicked the show into overdrive, 4000 fans - half of them going shirtless to escape the sweltering temperatures - tried out their best Tankian impressions, prompting the obviously chuffed singer to remark, "I'm proud to call this place home".
After a performance like that, System of a Down are welcome back anytime.
What: System of a Down
Where: Trusts Stadium, Waitakere
When: Wednesday, February 22
* What did you think of the show? Post your comments below.
