Ozzy Osbourne set for swansong at Black Sabbath hometown gig
Millions are also expected to follow online after fans snapped up tickets for the show, starring the original line-up, in just 16 minutes.
Osbourne, 76, who revealed in 2020 that he has Parkinson's disease, will join Tony Iommi, Geezer Butler and Bill Ward for the all-day "Back To The Beginning" show in Birmingham, central England, where the heavy metal giants formed in 1968.
The gig at Aston Villa Football Club's Villa Park stadium will also feature sets by US rockers Metallica, Guns N'Roses, Tool and Slayer among others, as well as a short solo set by Osbourne.
Around 40,000 fans are expected to watch the original line-up's first show together in 20 years and Osbourne's swansong.
The show comes as 1990s Britpop band Oasis play in Cardiff in the second of two concerts as part of another highly anticipated reunion.
"Birmingham is a city which means so much to Ozzy. When it comes to heavy metal music, Black Sabbath forming and his love of Aston Villa -– it all started here," his wife Sharon said in comments released by West Midlands Growth Company (WMGC), the region's investment and promotion body.
Black Sabbath have sold over 75 million albums worldwide and are widely recognised as one of the pioneers of heavy metal.
All profits from the show will go to charities including Cure Parkinson's and Birmingham Children's Hospital.
Osbourne's diagnosis led to him pausing touring. But Sharon told the BBC the Villa Park gig would be his last. "This is his full stop," she was quoted as saying.
'Greatest day'
Rage Against the Machine guitarist Tom Morello, musical director for the concert, said he plans "to make it the greatest day, the most important day in the history of heavy metal music".
The Smashing Pumpkins frontman Billy Corgan, who will also perform, added that "this might be the greatest one-day lineup in the history of rock 'n' roll".
The show is expected to deliver the area a multi-million pound boost, with hotel occupancy in Birmingham city centre expected to surge close to 90 percent, according to WMGC.
"The eyes of the world will be on Birmingham," said John Cotton, leader of the city council. "There is always such a special atmosphere in the city on major event days."
Osbourne's live performances at the height of his hedonism have gone down in rock folklore, particularly a 1982 gig in Des Moines, Iowa, when he bit the head of a bat on stage.
Osbourne says he thought a fan had thrown a fake rubber bat onstage, and it wasn't until he took a bite that he realised it was real.
"I can assure you the rabies shots I went through afterwards aren't fun," he told US TV host David Letterman in 1982.
But there are unlikely to be any repeat performances on Saturday, with the rocker mellowing in his old age.
To coincide with the concert, Birmingham Museum and Art Gallery is hosting an exhibition in honour of the city's famous son, displaying his awards, memorabilia and photographs.
The local police force also got in the mood, naming a litter of new puppies Ozzy, Toni, Geezer and Billie.