Sunset Blvd. begins previews at the St. James Theatre September 28.

They wanted up-tempo,” Nicole Scherzinger purrs in the insulated register of a pop star preserving her voice, “so I’ll do a fun little set of the hits.” You may know the hits yourself: Scherzinger is best known as the lead singer of the Pussycat Dolls, the aughts girl group whose songs touch a certain age bracket in the amygdala and get them on the dance floor. You probably remember the bravado of “Don’t Cha,” which suggests the listener wishes “their girlfriend was hot like me,” or the aural striptease of “Buttons.

” We are, at this moment, speeding down the FDR Drive in a black car on her way to a gig: a set under the Brooklyn Bridge at a Wimbledon watch party. A few days earlier, she was performing at a festival outside London. Even in a very short time talking to Scherzinger, you get the impression she is never at rest.

Her mind is always on to the next thing, the next comeback. We arrive at a makeshift dressing room in St. Ann’s Warehouse, and Scherzinger slips out of her poppy-red dress — deployed for a press appearance at the Empire State Building to promote this gig — and into a black sweat suit.

She checks in with the sound engineers, requesting alterations to the mix and reworking the song order. She corrects her dancers’ choreography. She asks her strapping young Irish PA, Liam, to stand in the grass in front of the stage and record video of soundcheck on his iPhone.

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