“Smash” star Megan Hilty sashayed into Rat Pack territory over the weekend, belting and crooning with a swinging National Symphony Orchestra in a pops concert titled “Luck Be a Lady” at the Kennedy Center’s Concert Hall. That Frank Loesser song from “Guys and Dolls” was Hilty’s opener, and the orchestra displayed a puncher’s attitude that seemed to go right to Hilty’s hips and spine, inspiring long, muscular phrases in her singing. The tune roared, and the big-band era was back.

Take that, Katharine McPhee! (McPhee plays Hilty’s rival on “Smash,” NBC’s ultra-dishy Broadway soap opera.)

Hilty looked glamorous — red strapless gown before intermission, black afterward — and shifted smoothly from kittenish whisper to vixen conquistador in Cy Coleman’s “The Best Is Yet to Come.” NSO principal pops conductor Steven Reineke, who included several vintage Nelson Riddle arrangements (and often swayed jauntily at the podium), injected a solid pulse into “Almost Like Being in Love” and “This Can’t Be Love,” a mashup that found Hilty dueting with the vocally sterling but almost too-laid-back Aaron Lazar.