They became the first married couple to ever enter the TV house during the series launch on Thursday (03Jan13) - but they were dealt a blow when they were ushered into the dingy basement.
In a cruel twist, half of the cast was taken into luxury accommodation and treated to a champagne reception, while the rest were sent downstairs, with basic rations and no running water.
Joining Montag and Pratt were Steps singer Claire Richards, former model Paula Hamilton, U.K. soap stars Gillian Taylforth and Sam Robertson and Australian actor Ryan Moloney.
Italian horse-racing jockey Frankie Dettori and former U.K. X Factor contestant Rylan Clark also became housemates.
Troubled Hollywood actress Lindsay Lohan is rumoured to be part of the new season of the show - but she did not make an appearance in the first episode.
The stars will now battle it out in a series of challenges and evictions to be crowned the winner when the game show wraps later this month (Jan13).