Here’s what to expect from Mariah Carey’s diva showcase — PHOTOS

Is this negotiable? Could we maybe trade one of those 18 No. 1 hits for an extra shot of crazy?

Mariah Carey’s custom-Vegas show unveiled Wednesday, and “No. 1 to Infinity” had challenges both declared and unspoken.

To call the Colosseum at Caesars Palace’s latest diva showcase predictable is kind of “no duh” when they’re actually making “predictable” a selling point. But when you combine the show’s pledge with the venue’s tradition of camp diva spectacles, there’s no other word for it — at least until it comes time for the star to speak.

The stated mission was unusually specific: Give fans the set list up front. The pop diva singing all her No. 1 hits from 1990 to 2008, and in chronological order, no less.

That may not seem like a big deal when any tour’s set list is a search engine away. But if you’re the one putting it together, the rules give up not only the element of surprise, but control over the pacing and the sequence of the songs.

And trying to do all this in 100 minutes doesn’t leave much room for the unspoken challenge: These days, Carey is of interest as much for what she says as what she sings.

Younger voices have taken over the airwaves and kept most of Carey’s recent singles out of the Top 10. Is it convenient, or a little awkward, that the format accentuates the positive and reinforces a body of work, while ignoring the last two studio album bombs?

But after growing up in the public eye, the 45-year-old has aged into this confidentially loco character. Whenever she opens her mouth, we can’t wait to hear what tumbles out.

Opening night didn’t leave a lot of room for improv. There was one intriguing moment when she felt the need to apologize to us “dah-lings” for drinking some water, and she didn’t like fans in the front rows being able to see what brand she was drinking: “Somebody’s getting a kickback because they always have the (label) facing the front.”

More of that good stuff, please!

Maybe some other night between now and May 24. “I’m doing my best to be a diva this evening,” she declared at one point, presumably meaning she was on her best behavior.

Another moment found her calling for “a moment of assistance” from her wardrobe team, tossing out some hard-to-follow logic about how she can’t be too much of a diva if she’s willing to “get dressed in front of the whole room.”

If by chance you came for the music, you found the singer’s voice mostly up to the challenge. If her vocals were less pristine and her range a little huskier for the years, the trade-off is a little extra character in songs that could usually use some.

Funny thing about all those Number Ones, and all the talk of how no other solo artist has matched that record. Fans who grew up with Carey may have been able to sing every one of them. But radio was well-fragmented into niche formats by the 1990s. For some of us, the reaction to some of these supposedly universal hits was more like, “Oh yeah. I think I remember that one.”

But this may actually aid the restrictive format. From “Vision of Love” to the new single “Infinity” (so far, the one exception to the ‘No. 1’ rule), the songs flow as smoothly as they do in any concert.

Director Ken Ehrlich (who also helms the Grammys and staged the more recent Celine showcase) supplies enough visual variety to keep them moving along. They cover all angles of Carey’s appeal, from nouveau-riche opulent to gay-camp ridiculous. “Touch My Body,” set in a projected version of Mariah’s mansion, even managed to combine both in one.

And the memories came back, though sometimes with visual aids. Trey Lorenz helped sing “I’ll Be There” just as he did way back in the “MTV Unplugged” days, and a video Michael Jackson even joined in by the song’s end. If “Hero” showed admirable restraint by not using any video of actual heroes, “Fantasy” followed with a full carnival set, balloons and bicycles.

Carey didn’t commit to as many dates as Celine Dion or Shania Twain, and so didn’t get quite the budget for production design. Except for a giant pair of butterfly wings that parted like glorified curtains, the show could easily go on tour.

Still, there’s a jaw-dropping attempt to recreate the 1997 “Honey” video. The old video with “Agent M” being interrogated (by Eddie Griffin, now working a few blocks away at the Rio) leads to Carey drifting out on a Jet Ski, getting an “Ann-Margret hoist” from male dancers in sailor caps, and not being afraid to show off some thigh, even if the thighs being shown off don’t match up to the ones in the poster ads all over town.

But this high-water moment of silliness was immediately followed by a tasteful flamenco guitar intro to “My All” and a shirtless dancer’s graceful solo (the choreography is by Las Vegas hometown heroes Tabitha and Napoleon D’umo).

We never want Carey’s mouth to be as formula as her songwriting. And somehow, against all odds, the show sometimes manages not to be either.

Read more from Mike Weatherford at bestoflasvegas.com. Contact him at mweatherford@reviewjournal.com.