It is understood that viewers will be given the chance to vote a former housemate back in for part of the final two weeks of the series, which is running for an unprecedented 12 weeks, two more than previous series.
Viewers are expected to be told of the twist on tonight's show, with media speculation already putting Nikki as a favourite to return.
Nikki has already become the latest darling of celebrity magazine Heat, which has helped keep a string of former housemates, most notably the show's richest contestant Jade, in the public spotlight.
The decision to reintroduce a housemate mirrors a move taken in the fourth series where housemate Jon Tickle was re-introduced to halt flagging ratings and counter criticism that the series was boring.
But while the current series has garnered similar criticism of being uneventful, ratings and crucially its share of the valuable 16- to 34-year-old market have held steady.
It is effectively the second time in this series that Channel 4 has brought back a housemate. Aisleyne was voted out, but then found herself in a secret part of the 'Big Brother' house with three other new housemates.
According to latest research from Barb figures over the year so far, the show has accounted for a fifth of Channel 4's 16- to 34-year-old audience. The show is also trouncing ITV rival show 'Love Island' in the ratings.
Also on tonight's 'Big Brother' viewers will see which of Mikey, Susie, Jennie and Imogen will be the latest housemate to be evicted.
Liverpudlian Mikey, who has spent much of this week arguing with his other housemates, is 2/5 for the boot with bookmakers. Susie, who won a golden ticket to enter the show as part of a link up with Nestle's Kit Kat, is second favourite for the axe at 7/4.
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