Britney Spears’ sixth album doubled as her late-2000s soft reboot; while it possessed some of the glitchy instrumentals and self-lacerating lyrics of its predecessor, 2007’s hedonistic Blackout, it felt brighter and more commanding from the siren-call opening note of its leadoff track, “Womanizer”. Brisk and accusatory—“boy, don’t try to front, I-I know just-just what you are,” Spears chides on its quick-stepping chorus—“Womanizer” features Spears vacillating between flirtation and irritation in her efforts to stand up for herself and any other women who might fall prey to the “swagger of a champion”. Those lyrics and the stomping beat—a key facet of many uptempo pop cuts from that era—effectively reintroduced Spears to the world while also showing how she’d grown since the days of “I’m Not a Girl, Not Yet a Woman”. Spears’ serpentine voice is used to great effect on Circus’ speedier offerings, with the anti-hater broadside “Kill the Lights” a particular highlight. Produced by Nate “Danja” Hills, who had worked on Blackout standouts like the giggly “Gimme More” and the freestyle-nodding “Break the Ice”, it uses blown-out synth horns to punctuate her snarling rebukes. Its use of the phrase “feeling froggy” provides the sort of levity that made Spears so appealing early on; although she took her craft seriously, she wasn’t above dropping silly one-liners to make herself crack up. (See also the sing-song “If U Seek Amy”, the punny title of which caused pearl-clutching among the what-about-the-children set.) But Spears can get serious to arresting effect; “Unusual You”, produced by “Toxic” hitmakers Bloodshy & Avant, represents the haze of early attraction with fuzzed-out synths and a dreamy vocal performance, while the Danja-helmed “Blur” is a slow-burning morning-after rumination with keyboard filigrees accentuating Spears’ attempts to put together pieces of the night before. And the pouting “Radar” bridges the space between Blackout and Circus; originally intended as a Blackout single but reintroduced here, its club-ready sonics and Spears’ carefree performance show how the dark period she had just emerged from left its mark on her sound and provided her a path to pop’s next level.