“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.

Lazar had a couple of featured moments, the best being “Night and Day” as the orchestra, playing with verve, successfully lit a fuse under the singer’s slow-burning dynamism. Reineke showcased the NSO with “Unchained Melody,” rendered with impeccable delicacy by the string section but still a snooze. The gaudier selections — the rhythmically irresistible “Tico-Tico No Fuba” and a louche, squealing “Goldfinger” — made deeper impressions.

Maybe everyone was just primed for Rat Pack swagger. Hilty, who recently drew raves for her New York concert turn in “Gentlemen Prefer Blondes,” privileged vocal brass over lyrical sass in “Diamonds Are a Girl’s Best Friend,” a song that finished three separate times (big, bigger, biggest). She went out with a thrilling bang, ripping through the manic Judy Garland arrangement of “Come Rain or Come Shine.” The performance sounded like an ecstatic nervous breakdown, and it brought a good part of the crowd to its feet.

Megan Hilty belted out Broadway hits in a pops concert with the National Symphony Orchestra at the Kennedy Center Concert Hall. (Curtis Brown)