The Channel 5 show's bosses are concerned that glamour model Rhian Sugden and Simon Cowell's ex Jasmine Lennard could "fly into a rage", according to the Daily Star.
Sugden and Lennard reportedly dated Portuguese football ace Ronaldo at the same time during his stint at Manchester United.
Meanwhile, there are also concerns about Sugden and TV presenter Coleen Nolan, because of the model's sex text 'affair' with Vernon Kay.
Nolan is close friends with Kay's wife Tess Daly.
Celebrities rumoured to be taking part include Duane Chapman aka Dog the Bounty Hunter, former EastEnders actress Cheryl Fergison, Sex, Lies and Rinsing Guys documentary star Danica Thrall, So Solid Crew's MC Harvey, comic Julian Clary and Corrie icon Julie Goodyear.
Channel 5 ordered a second run of Celeb Big Brother for 2012, following the ratings success of the Denise Welch, Michael Madsen and Frankie Cocozza series in January.
The Celebrity run will last 23 days.
Watch Brian Dowling talking about Celebrity Big Brother below: