Robert Plant & Alison Krauss Tonight and Tomorrow at MSG Theater

T-Bone Burnett will tell you it was the beauty of their voices that compelled him to make Raising Sand with Plant and Krauss. The group's love of American roots music helps it apply a modern blues-rock sensibility to stylized bluegrass melancholia, inspiring both singers to indulge the mellower end of their vocal abilities. Fragments of Led Zep and Union Station still collide on tracks like "Nothin'," but it's singing guitarist Rosetta Tharpe (who pioneered influential fusions of country, gospel, blues, and swing in the '30s and '40s) who is the patron saint of Raising Sand, as the psalmodic "Sister Rosetta Goes Before Us" makes exhilaratingly clear. CAROL COOPER.

8 p.m., $40-$100. Theater at Madison Square Garden, Seventh Avenue & 32nd Street, 212-465-6741.

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Talking with Robert Plant