Black Eyed Peas and Chris Brown are the latest acts to pull out of the Michael Forever concert at the Millennium Stadium in Cardiff, Wales on 8 October.
The Black Eyed Peas cited “unavoidable circumstances” for cancelling at the last minute, while Brown was unable to obtain a UK visa.
They follow in the footstep of KISS who were originally due to play but were uninvited following previous comments made by bassist Gene Simmons about Michael Jackson’s child abuse allegations.
3T, Alexandra Burke, Alien Ant Farm and Cee Lo Green will all still perform this weekend alongside Christina Aguilera, Craig David, Diversity and Gladys Knight.
Jennifer Hudson, JLS and Latoya Jackson are also on the Michael Forever line up alongside Leona Lewis, Ne-Yo, Pixie Lott and Smokey Robinson.
Beyonce will perform via a video link.
Plans to stream the entire show on Facebook have also been cancelled as organisers failed to get licences from publishers for the songs that are due to be played at the event.
Those who had already paid to stream the show will be refunded, say organisers.