Grammy Award-winning group Lady Antebellum perform to a packed house at Merriweather Post Pavilion in Columbia, Md. (Kyle Gustafson/For The Washington Post)

Lady Antebellum is proof that social life isn’t always so awkward for the proverbial third wheel.

At the Nashville trio’s appearance at Merriweather Post Pavilion on Sunday night, Dave Haywood played free-floating utility infielder to Charles Kelley and Hillary Scott’s electrifying guy-and-girl duo act.

On emotionally raw songs like “Just a Kiss,” “Love This Pain,” “I Run to You” and “Need You Now,” Kelley and Scott leaned in close to trade lead vocals and harmonies; the peripatetic Haywood occasionally pitched in with backup vocals, but mostly kept busy on a bevy of instruments including guitar, banjo, mandolin and piano.

Somehow it all worked seamlessly.

Lady A, as the trio is known to its growing legion of fans (Merriweather was packed and ear-splittingly loud), is also notable for its lack of even perfunctory nods to traditional country. With a slick stable of backing musicians, Lady Antebellum is more like a straight-up contemporary pop collective.

When Scott gathered all performers center stage, she said it was time to “bring a little Nashville to Maryland.” After an endearing “American Honey,” that time passed quickly. Warm-up acts Thompson Square and Darius Rucker joined in for covers of the Allman Brothers Band’s “Midnight Rider” and the Doobie Brothers’ “Black Water.” Later came a raucous version of the Stones’ “Honky Tonk Women,” during which guitarist Jason Gambill heroically completed a solo despite being tackled by a horseplaying Kelley.

It’s probably more accurate to say that Lady Antebellum brought Nashville to Maryland for its entire 90-minute set. Nashville means many things these days — including the kind of polished pop-rock the group plies.

Sunday’s set was well-paced with breezy fare such as “Perfect Day” and “Lookin’ for a Good Time,” but it’s the sweet blend of voices that justifies the price of admission.

On everything they write and sing, but especially the hit single “We Owned the Night,” Lady Antebellum produces harmonies that can induce goosebumps.

Galupo is a freelance writer.