I wasn’t going to post this on my theater blog because it’s a pop music review, but there’s actually a fine line between a pop concert — especially one as lavish as this — and theater these days. So what the heck — here’s my review of Christina Aguilera’s concert at Oakland’s Oracle Arena on Thursday, March 8.

Aguilera still dirrty even as she goes back to basics

When Christina Aguilera begins to prance around the stage in crotchless black lace pants (not to worry, she’s wearing a Betty Grable-ish white one-piece underneath) singing “Still Dirrty,” the giant screens behind her fill with images of phony newspaper headlines. “From dirrty to demure,” reads one. “From crass to clean” and “From freak queen to squeaky clean” read some others.

Has the 26-year-old former “Mickey Mouse Club” performer and later _ during her “Stripped” era _ skank queen really cleaned up her act that much?

The answer is: sort of.

At Oakland’s Oracle Arena Thursday night with her Back to Basics tour — which plays San Jose’s HP Pavilion Saturday (March 10) — Aguilera proved she can still bump and grind with the best of them. But Aguilera’s a married woman now, and after some canny career moves, she’s well on her way to becoming a grown-up and, dare we say it, classy performer.

With a song list taken mostly from her latest double disc, “Back to Basics,” which purports to be a modern take on jazz, cabaret and pop from the ’30s, ’40s and ’50s, Aguilera is still showcasing her dynamic pipes — the most distinctive in pop music, at least until Whitney Houston decides to come back — dancing up a storm and showing the world what an empowered, sexually liberated, totally in control pop star looks like.

What the show lacks is that defining moment when Aguilera strips away the elaborate staging, the 20-strong band, the eight dancers and the 10 costume changes (all by Roberto Cavalli, no less) and just sings.

During “Hurt,” a wrenching ballad from the new album, and at the start of her encore with “Beautiful,” it looked like we were going to get an unadorned Aguilera. But a nearly sold-out arena is just too big for such intimacy, and both tunes turned into full-throttle production numbers.

Though Aguilera had a hand in writing all the songs on her new album, it was hard to distinguish lyrics in her songs. Part of that is simply the muddy acoustics of an arena show, and part of it is Aguilera’s style of over-singing. We may not hear distinct words, but we hear the money notes when she adds her cascading “hey-yeahs” and “wo-hos.”

That’s probably why the upbeat tunes provided her 95-minute set with its best moments. Show-opener (and recent Grammy winner) “Ain’t No Other Man” gives Aguilera her best opportunity yet to be sexy, funny and classy all at the same time.

“Candy Man” is a naughty riff on the Andrews Sisters that puts the X in Xtina, and “Lady Marmalade,” performed as if in a New Orleans boudoir during Mardi Gras, proves Aguilera can do just fine without Lil’ Kim, Mya or Pink, thank you very much.

Concert director and choreographer Jamie King’s best work is with the eight dancers — four men and four women — whose moves are so hot they could be a show all on their own. They provide much of the evening’s zest, as does the lively four-piece horn section.

But this is Aguilera’s circus, and she is definitely the ring mistress. She does a pole dance while straddling a carousel horse during “Dirrty,” tortures (in a nice way) a male member of the audience during “Nasty Naughty Boy,” pays tribute to her mom with “Oh Mother” and puts a reggae spin on one of her early hits, “What a Girl Wants.”

Part Cher and part Elton John, Aguilera does some old-fashioned entertaining with some new-style vocal blasting. When her new album came out last year, there was talk of her doing a small club tour. Of course that didn’t happen. When you can sell out arenas, you don’t sing in smoky cabarets. But if the day ever comes when Aguilera truly strips it down and focuses in on the music — when she actually goes back to basics — that will be the show to see.