Review: Rihanna at the Wells Fargo Center in Philly

Given all of Robyn Rihanna Fenty's well-documented troubles, laryngitis would seem to rank fairly low. But it was throat trouble that made Thursday's show at the Wells Fargo Center the second of her Diamonds World Tour rather than its fourth, after she canceled gigs in Boston and Baltimore.

Rihanna's voice wasn't 100 percent on Thursday, although as she was often augmented by prerecorded double- and triple-tracked vocals, as well as a pair of backing singers, the crack in her throat was more evident when she spoke between songs. The stage, frequently reconfigured to keep pace with her half-dozen costumes changes, was littered with clusters of water bottles, and near the end of her hour-and-45-minute set, she asked for more over a live microphone mid-song - a rarity in the highly managed world of arena pop productions.

Such deviations from the script were rare. The set list for Friday's show duplicated the one from the tour opener in Buffalo, although with the second and third sections transposed. Moving up the comparatively spartan section built around the reggae of Rihanna's native Barbados and saving the jet-fueled pop of "Jump" might have given her a slight breather, but with a tour currently scheduled to run through October, some early-stage tweaking is par for the course.

Depending on whom you ask, Rihanna is either an endlessly versatile performer or a vacant vessel, a chameleon or a cipher. That's as true of her life as of her art, especially when it comes to her troubling relationship with the performer Chris Brown, who pled guilty to assaulting her in 2009. Their on-again/off-again relationship is currently on, although "Nobody's Business," the defiant but confused duet with Brown from her album Unapologetic, was notably absent from the set. Brown wasn't there, of course, but neither were Kanye West, Eminem or Drake, which didn't stop Rihanna from performing her part of their recorded collaborations.

Rihanna outsourced the high notes of "Umbrella" to her backing singers, often letting them carry the song, but she mouthed the words off-mic like a fan with the best seat in the house.

The show lacked an animating intelligence that might have united its disparate strands and at times the scattershot style seemed random, almost desperate. Why, for example, did the visuals for "Rockstar 101" feature slasher-movie clips and a red-tinged Rihanna wielding a chainsaw? (Another segment featured her wearing a jumpsuit akin to Uma Thurman's Kill Bill getup; perhaps she's been watching too much Quentin Tarantino.) But Rihanna gave herself equally to every new arrangement. She may not know who she is, but she knows where she wants to be.