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The boys will be joined by Cee-Lo Green, Christina Aguilera and members of the Jackson family.
Also set to perform at the star-studded concert are Leona Lewis, Craig David, Alien Ant Farm and Smokey Robinson, with other acts set to be announced in the next few days, the promoters told CNN.
Members of the Jackson family taking the stage October 8 in Cardiff include several of Michael Jackson's brothers, "The next generation of Jacksons," and 3T, which consists of Tito Jackson's three sons.
"This announcement is just the beginning, we have many more to announce," Global Live Events executive Paul Ring said. "This concert will unite various generations and musical genres, reminding everyone of just how amazing a talent Michael was."
With the "Michael Forever: The Tribute Concert" line-up now known, fans can start "registering their interest for tickets" online at www.michaelforevertribute.com, beginning Thursday, the promoter said. A lottery will determine which fans will be invited to purchase tickets.
The concert in the Wales Millennium Stadium in Cardiff, which seats 75,000 people, would be at least four hours long, Global Live Events CEO Chris Hunt said.
"We're playing where?" Aston and the boys were no doubt delighted when they found out.
(Pic: The boys backstage at a recent gig)