Mariah Carey -- I'm Back at Caesars!! Fans Highly Doubt It

Mariah Carey has the green light to perform Saturday night at Caesars Palace in Vegas, but Mimi's fans are still skeptical about whether she'll make it to the stage.

Sources at the hotel tell us the box office has been flooded with calls today from gun shy fans who are concerned they're going to get stiffed like the crowd did on Wednesday ... when Mariah had to cancel due to bronchitis.

If it's any consolation to the worry worts --- our Mariah sources say all signs point to MC performing. Doctors cleared her, and she attended a rehearsal. In order to save her voice, we're told she whistled the songs ... and even that sounded pretty good.