Black Sabbath have been on a massive high this year, releasing the comeback album '13,' which debuted at No. 1 on the Billboard album charts, while embarking on an insanely anticipated North American tour. Sabbath bassist Geezer Butler has performed phenomenally throughout the entire tour, but in a new interview, Butler reveals that the tour will likely be his last.

Black Sabbath's reunion ran into some unexpected speed bumps fairly quickly after the Nov. 11, 2011 announcement of the band's return. Guitarist Tony Iommi's cancer diagnosis and drummer Bill Ward's failed contract negotiations held up Sabbath's touring plans for an entire year, but the iconic heavy metal outfit has emerged triumphant. '13' gave Sabbath their first U.S. No. 1 charting album in the band's history before Black Sabbath's highly successful North American tour began on July 25.

Despite Black Sabbath's monumental achievements, Butler reveals to the Chicago Sun-Times that his time in the band may be coming to an end. "I’ve always said as long as I can play, as long as I can do it to a good level, then I’ll keep doing it, because I still really enjoy playing," says Butler. "I’ll know when the day comes I can’t do this anymore, can’t play to my usual standards. That’s when I won’t go out anymore. I won’t do that to me self. But at the moment, I just love playing with the band. It probably will be the last time, will probably be the last tour. But I want to go out on a high. The band is playing really well at the moment."

"I don’t know. I just got a feeling," Geezer adds after being asked why. "It’s getting tough, it really is. I can’t lie about that. I’m old now. It really is tough going on every night. You wake up next day, all the pains you never had before. I don’t want to go onstage for the sake of the money. You have to have a lot pride in yourself, and I honestly think I’m coming to the end of the top of my job."

Black Sabbath still have a handful of North American tour dates left, so if you're a mega-fan or even just curious about the group, make sure you catch them while they're still around! We were lucky enough to catch Sabbath at their Aug. 4 show in New Jersey. Check out our recap + photo gallery from that gig here.