Black Sabbath's final show is two months away, and Geezer Butler's "already having palpitations."

The bassist spoke about his nerves and the pressure he feels ahead of the monumental gig during an interview with The Guardian. “I’m already having palpitations,” he admitted. “In fact, I had a nightmare last night.”

“I dreamed everything went wrong on stage and we all turned to dust,” Butler recalled. “It’s important that we leave a great impression, since it’s the final time that people will experience us live. So it has to be great on the night.”

During the same interview, Ozzy Osbourne spoke about his involvement and why he's worried fans might feel "ripped off" if they attend the concert.

“We’re only playing a couple of songs each,” Ozzy divulged. “I don’t want people thinking, ‘We’re getting ripped off,’ because it’s just going to be … what’s the word? … a sample, you’re going to get a few songs each by Ozzy and Sabbath.”

Fortunately, the day-long Back to the Beginning event will also feature performances by several other icons in the rock world, and the lineup recently got more impressive because Ozzy's wife Sharon Osbourne revealed that Aerosmith's Steven Tyler and the surviving members of Soundgarden were added to the bill. Last month, Ozzy spoke about how he's begun "heavy training" to get ready for the show, and during his conversation with The Guardian, he confirmed that this would definitely be the last time he performed live.

“I’d love to say ‘never say never’, but after the last six years or so … it is time,” the 76-year-old said. “I lived on the road for 50-odd years, and I’ve kind of got used to not picking up my bags and getting on the bus again. I don’t smoke dope or do any of the rock star lifestyle any more. I’m kind of like a homebody. I never go out. I never hang out in bars – I don’t drink.”

“So what the f**k is out there for me? I hate going shopping with my wife. I feel like stabbing myself in the neck after half an hour," he added. "But it’s time for me to spend some time with my grandkids, I don’t want to die in a hotel room somewhere. I want to spend the rest of my life with my family.”

Back To The Beginning and is to take place July 5 at Villa Park in Birmingham, UK. The all-day event will also feature sets from Metallica, Slayer, Pantera, Alice in Chains, TOOL, and many other rock and metal icons.