"Y'know, retirement is like anything," Johnson tells Morning Sun Music. "A good footballer, a good ice hockey player, they don't want to retire, but unfortunately sometimes there's a time when you have to call it quits. So it's an ongoing thing with us; we never say no, and we never say never.

"The thing about the boys in AC/DC, you've got to remember, is we're constantly surprised and amazed at how we keep the success going. We don't know what we're doing - I mean, we literally don't know what we're doing except what we're doing is we just play 100 percent every night and give it everything we've got. If that's the secret of success, we'll pass it on."