Around 3½ minutes into Megadeth's High Speed Dirt, a track off their iconic 1992 record Countdown to Extinction, the brutal riffage is momentarily interrupted by an acoustic, bluesy lick.
At first, it seems at odds with the rest of the song, and indeed, the album as a whole, but given the blues is where metal came from, it also feels oddly relevant, sitting comfortably among the guttural thrash the band does so well.
''Oh yeah, the Elvis part,'' laughs frontman and guitarist Dave Mustaine.
''Yeah, that's my Elvis part. I think we were just doing a goof on Blue Hawaii, because Marty [Friedman, lead guitar] loved Elvis so much ... it was always fun to play with him.''
Mustaine, known as much for being one of Metallica's original guitarists as he is for founding Megadeth in 1983, is talking about various aspects of Countdown because, and he struggles to believe this as well, it's an album that is now two decades old.
As such, the band he and bassist Dave Ellefson allegedly began as a middle finger to Metallica (who fired Mustaine before they released their 1983 debut, Kill 'Em All), have recently released a live version of the album, recorded last December at Los Angeles' Fox Theatre.
''It was fun,'' muses Mustaine, on revisiting the record after 20 years, an exercise which included a US tour where the band played the album in full, something they also did in 2010 for the 20th anniversary of 1990's Rust in Peace.
And it's a fitting tribute, with Countdown to Extinction being one of thrash metal's all-time classics.
''When you're listening to one of your records, and people have said something like, 'this is a classic' or something, you immediately, and I don't know how to say this without sounding like I'm having a hard time saying it, because I'm having a hard time saying it,'' he says with a laugh, ''but when people say stuff like that, a lot of times it's hard not to come off sounding like you know that.
''But we knew when we were making Countdown, we just knew we were in the middle of making a good record.''
Arguably, their first five records (Countdown being the fifth) were, as the man modestly puts it, good. Megadeth, with the release of debut Killing is my Business ... and Business is Good in 1985, quickly established themselves as one of the big four thrash bands, along with Metallica, Slayer and Anthrax, effectively playing a major part in the invention of this particular brand of heavy metal.
''Yeah, I've sat back and watched it [over the years], and have participated in it, too [obviously], and it is kinda hard to do both,'' he says on one of metal's most popular veins.
''And there's definitely been a lot of changes over the years ... and with technology. In the beginning, it was so difficult, now you just press the red button and away you go.''
The band, which released its 14th album this year (almost 28 years to the day after their debut), has now been around for almost three decades, an incredible achievement in anyone's book. And while Mustaine has a reputation for being somewhat of a tainted character (before you interview him, you get the now ubiquitous, ''No questions about Metallica, drugs or religion'' ultimatum), you can't deny he's one of metal's greats and that the band he created is worthy of legend status.
''Time flies, 30 years seems like a long time, but boy, it's over so quick,'' he marvels. ''Sometimes I sit back and think how many things have happened over the years, and I guess the thing that makes me feel the best is when I see how many people who'll say, 'We met at a concert', 'We got engaged at a concert', 'We got pregnant at a concert', all these things that they share. These landmarks, these mementoes, they're really cool.''
The band are now on tour in the US, and will head back to Australia in February for the Soundwave festival. They're working as hard now as they were in the early '80s, and listening to Mustaine talk, you get the impression the only thing that'll stop this heavy metal juggernaut is old age and no longer being able to physically perform this incredibly technical and demanding music.
''I never thought I'd be doing this this long, David Ellefson and I; it's crazy,'' he says. ''And the fact we can have fun doing what we do, on top of that, just makes it so much more enjoyable.''
Megadeath play Westfest in Auckland's Vector Arena on 19/20 February.
- The Age