EXCLUSIVE: Julie Chen on 'Big Brother' Evictee Who Poses the Biggest Threat in a Battle Back Challenge

Big Brother host Julie Chen -- just like everyone else -- is on the edge of her seat to see how the show's first Battle Back challenge will turn out.

"We have never thrown someone back in the house after they have been evicted so early in the game," Chen told ET. "Whoever wins, you're going to see them back in the house and the expression on all the houseguests' faces."

WATCH: The First 'Big Brother' Battle Back Competition Is Beyond Intense

The unprecedented challenge gives the first five evictees a chance to return to the game by competing in a series of obstacles a la the Head of Household competition.

The first head-to-head battle is between Glenn, the season's first evicted houseguest, and Jozea, who was eliminated second. The winner will go on to face the next evictee until an ultimate champion is decided.

"I. Am. Here. To Play," Jozea says in a preview clip.

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Out of all the evictees, Chen guessed that Tiffany's possible return could be the most dramatic if she wins the Battle Back competition.

"They haven't done anything for her for two weeks now, and even up until before she just got evicted, there was some talk about flipping the house," Chen explained. "She would be the biggest threat. She has revenge on her mind, so we will see if it's her."

The special episode of Big Brother airs Friday at 8 p.m. ET/PT on CBS.