AGUILERA, TIMBERLAKE MOVE MUCH BUT FAIL TO BE MOVING.

Byline: Bill Hetherman Staff Writer

WHAT IS PERHAPS the biggest pop extravaganza of the summer rolled into Staples Center Monday before a capacity crowd as Christina Aguilera and Justin Timberlake drove a show laden with glitter but lacking in soul.

The two former Mouseketeers, performing the first of three nights at Staples, are telling their fans that, at age 22, they want to be seen as mature singers as they promote her ``Stripped'' and his ``Justified'' CDs.

To some extent, they succeeded. Aguilera took the stage first, opening with ``Dirrty,'' reaching into the past with ``Genie in a Bottle'' and not forgetting ``Lady Marmalade.''

But Aguilera's most touching number was ``Beautiful,'' her encore offering. By then she had ridded herself of leather garments, corset and lace stockings in favor of a pair of jeans and a T-shirt that said ``God Sees No Color.''

The song exemplified the cross-cultural appeal she and Timberlake have generated.

And in ``Impossible,'' which she recorded with Alicia Keys, Aguilera showed she can generate more heat sitting atop a piano than shimmying as she did for the majority of the night.

However, in an exchange earlier with one member of her dance troupe, Aguilera sounded childish when she told him he couldn't take a cue from her current album's title and strip off her clothes.

``Only if I let you,'' Aguilera said.

The obvious rut in staging such a huge production is that both artists are stuck with pretty much the same show every night. In the age of the Internet and the sharing of concert music via cell phone with friends at home, many fans knew from their previous concerts what Aguilera and Timberlake would sing and what they would say.

A nice surprise from Aguilera would have been to hear something like Sylvia Mason-James' version of ``Live for Today'' instead of Etta James' ``At Last.''

In either song, Aguilera could demonstrate the prowess of her magical voice by hitting the high notes and holding them a long time.

As for Timberlake, the clear crowd favorite borrowed heavily from the ``Justified'' CD with ``Cry Me a River,'' ``Rock Your Body'' and ``Senorita.''

Not to be outdone by Aguilera, Timberlake also climbed atop a piano for ``Still on My Brain.''

He also offered a frenzied ``Girlfriend'' to satisfy the fans' passions for N'Sync material.

But Timberlake, the far better dancer of the two, spent too much time beat-boxing with his band while hovering in a cherry picker that extended over the crowd.

Both performers should consider scaled-down shows next time with fewer dancers, backup singers, stairwells and props.

They also should take risks and say a little more in their music. Madonna recorded ``Papa Don't Preach'' (a song about an unexpected pregnancy) early in her pop career and didn't care if there was a backlash.

That's the bridge Aguilera and Timberlake need to cross if they really aspire to be mature artists.

Aguilera and Timberlake will end their stint at Staples Center Friday.

JUSTIN TIMBERLAKE AND CHRISTINA AGUILERA - Two and one half stars Where: Staples Center, 1111 S. Figueroa St., Los Angeles.When: 7:30 p.m. Friday. Tickets: $42.50 to $68. Currently sold out, but some tickets may be released. Call [phone] or go to ticketmaster.com.

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Photo: (1 -- 2 -- color) Christina Aguilera and Justin Timberlake, shown at a recent performance in Arizona, delivered plenty of spectacle but not enough substance at Staples Center Monday. Rob Schumacher/Arizona Republic