Rancid guitarist Lars Frediriksen must be one of the hardest-working men in the entire music business, let alone the world of punk rock.
He's in three bands, plays guitar occasionally with three others, and is an in-demand producer who's worked with the likes of Dropkick Murphys and Agnostic Front.
Old Firm Casuals are a 'sideline' he formed eight years ago with bassist Casey Watson and drummer Paul Rivas, veterans of the hardcore scene in his native San Francisco, California.
Joined by guitarist Gabe Gavriloff, the Casuals quickly made their mark on the scene with a series of well-received 7in singles, EPs and contributions to compilations on a variety of labels.
A debut album, This Means War, in 2014, showed the band was more than a passing fad for Frederiksen, and this show is part of a tour to promote its follow-up.
The new record, Holger Danske, is named after the Danish legend that never died, but was only in a deep sleep until summoned to protect Denmark.
It's a magnificent mix of punk, hardcore and heavy rock, and looks set to cement their reputation as a must-see band - and not just because there's a bloke from Rancid in it.
Make no mistake; while Frederiksen takes centre stage, the Old Firm Casuals are by no means all about him, with each member bringing something to the table.
Watson shares vocal duties as well as playing a mean bass, Gavriloff a guitar player full of power chords and flourishes, while Rivas lays down a thunderous backbeat.
I'd seen them once before, at Rebellion Festival, but hadn't realised just what a powerful, finely-honed outfit they are; something the 1,200-capacity Riverside showcased perfectly.
First, two North East bands of very different vintage warmed up the crowd, who might not have quite filled the venue, but made a damn good attempt at it for a Thursday night.
Openers Boilermaker, from Darlington (not to be confused with a 90s Californian band of the same name), were only formed a couple of years ago, and play tough streetpunk.
Comprising four fellas who've served their time in other bands, they get better every time I see them, and are adding new songs to their set as they prepare to make a follow-up to last year's excellent debut album Shop Floor.
Next up were Crashed Out, from Jarrow, stalwarts of the North East punk scene for more than 20 years, and good friends with Lars Frederiksen, who's even been inked at singer Chris Wright's Viking Tattoo Studio on previous visits.
Anyone who's seen the 'Oots' knows they play an infectious brand of street rock 'n' roll, and they were in their element in front of basically a home crowd. One Of The Boys, The Town That Died, Cushy Butterfield and, of course, The Jarrow Song slipped down a treat before the main course.
Then it was time for the Old Firm Casuals, who showed they meant business from the off as they tore into Get Out Of Our Way, the opening track from the new album, and followed it up with crowd-pleaser Perry Boys, one of the standout songs from their first record.
Five more tracks from the new album got an airing, including the anthemic Motherland (dedicated to Crashed Out), Casual Rock-N-Roll (the best song AC/DC never wrote), and the barnstorming Traitor.
There were also half a dozen from the first album, with the title track, Apocalypse Redux and Off With Their Heads the pick of the bunch.
No, the Casuals are not for the faint-hearted. They're angry, political, and fiercely anti-fascist, and scarcely paused for breath as they smashed through 17 songs in an hour.
There was no encore, but after the show they'd just seen, the audience weren't too disappointed. It's a couple of years since the Casuals last played in Newcastle. On this form, let's hope it's not too long before they're back.