American Idol, The Voice, America's Got Talent: ya seen one, you've seen them all, right? Maybe not.

The Four, Fox's latest entry into the field, flips the script on the singing competition by making four people who've already been selected by judges DJ Khaled, Megan Trainor, Sean "Diddy" Combs and music executive Charlie Walk defend their spot against new contestants over six weeks — or get the boot.

"It's almost like Hunger Games a little bit," says Fergie, host of the show. "They can be tough." Diddy likened it to Game of Thrones, or a schoolyard brawl, in which onlookers instigate the challengers to fight. In this case, the onlookers are the audience, which can decide in real time if a newcomer should dethrone one of the four. Challengers can vie to be on the show through social media and be on the stage as soon as a week, executive producer David Friedman said, which promises something new around the corner virtually The Four's whole six-week run.

Charlie Walk, Meghan Trainor, Sean "Diddy" Combs and DJ Khaled - The FourCharlie Walk, Meghan Trainor, Sean "Diddy" Combs and DJ Khaled - The Four

Think of it as Idol, gladiator style.

Not only is the competition geared differently than shows like The Voice, where constructive criticism is key, The Four's innate clash means judges, who'll help develop the winner's career, aren't as much coaches as they are tell-it-like-it-is execs with extremely discerning criteria for who they'll take on. Although Fergie, as host, describes herself as as more of a nurturer to contestants, the others aren't so lovey-dovey; even sweetheart Megan Trainor gets right to the point.

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"A lot of times we'll say no," she said at the Television Critics Association winter press tour in Pasadena Thursday. "I'm brutally honest. I tell them what I think, but I do sandwich it." She can recall, after all, being a terrified teenager herself playing a ukulele to a room full of execs and experiencing rejection after rejection as recently as four years ago, before she became a Grammy-winning singer-songwriter with a hit that sold 11 million copies worldwide. ("All About That Bass.") She'll tell contestants that she gets what it's like to be a little off or nervous, but ultimately, even she gives it to them straight. One contestant, in fact, hears her say, "I don't feel like this is what you want to do with the rest of your life." Ouch.

But for those who do get praise, they get a chance at the top prize: hands-on guidance from the judges, a recording contract and support from iHeartRadio, ensuring radio play.

The Four premieres on Fox Thursday, Jan. 4 at 8/7c on Fox.