Not long ago, in those dark days of 2007, it was conventional wisdom that Britney Spears might have problems getting through a Rorschach test, never mind a full-scale, Las Vegas-style concert extravaganza. And yet, there was Spears Tuesday night at Tulsa's BOK Center, performing as if all that tabloid mess had been scrubbed from the collective memory. No, she had not been magically transformed into a stunning singer, but Spears made her initial reputation as a performer, and at the BOK Center, she was performing. Following abbreviated sets by Kristinia DeBarge and former "American Idol" champion Jordin Sparks, the Barnum & Britney lights went up, and the Big Apple Circus took to the three rings on the floor of the arena, bouncing on trampolines and spinning chrome-plated giant cubes. After all, this was "The Circus, Starring Britney Spears," so the concert began with a surplus of human feats of strength and agility before Spears, 27, descended from the rafters in an egg-shaped cage. This was a tightly choreographed "Circus," and not just in terms of dance: the concert moved quickly and with metronomic precision. Spears danced and worked as a magician's assistant during performances of "Circus" and "Piece of Me," and acrobats spiraled from the ceiling on long silk scarves as a prelude to "Radar." Then Spears moved away from the big tent theme and into a martial arts concept piece for "Ooh Ooh Baby" and "Hot As Ice" and an elaborate bicycle routine for "Boys." Then, just as she did during a Sept. 5 performance in Greensboro, N.C., Spears temporarily shut down all the flash and spectacle and performed a cover of Alanis Morissette's "You Oughta Know." More so than at any other time during the two-hour concert, Spears appeared to be actually singing, and her faithful rendition of "You Oughta Know" provided a refreshing realism to the set. Having largely surprised the Tulsa crowd with the Morissette song, Spears returned to massive dance sequences with a Bollywood-inspired performance of "Me Against the Music." And after emphasizing her more sexualized material such as "Freakshow," "Breathe On Me" and "Get Naked," she closed out her main set with two of her best-known hits, "Toxic" and "Baby One More Time." There would be no massive encore: Spears performed "Womanizer" before she and her dancers bowed and exited to the strains of "Circus." Call it an expectations game or grading on a curve, but for a good portion of this decade, Spears did little to inspire confidence that she could put on such a show. At this point, she is far from embarrassing herself or going through the motions as she did during that memorably shambling performance on the MTV Video Music Awards just two years ago. She looked good, was energetic and proved fully capable of being the ringmaster for this "Circus." And for the approximately 16,000 fans gathered in downtown Tulsa, that was more than enough.