"Tom Waits, Peggy Lee -- why not?" said Diana Krall while zigzagging across the pop and jazz landscape at Merriweather Post Pavilion on Saturday night. The Grammy-winning jazz singer and pianist could just as easily have mentioned the names of other rarely linked composers who contributed songs to her quartet's performance: Mose Allison and Cole Porter, Nat King Cole and Chris Smither, Harry Warren and Joni Mitchell. Then, too, there were several songs crafted by a pair of newly wedded tunesmiths: Krall and Elvis Costello.

The marriage certainly seems a happy one from a musical standpoint. The songs composed by the pair for Krall's recent CD, "The Girl in the Other Room," consistently complemented her repertoire of standards and overlooked gems. Some unfolded as curious, open-ended vignettes (the album's title track), others were vividly descriptive ("Departure Bay"), and even Costello's classic ballad "Almost Blue" seemed tailor-made for Krall's dusky contralto and languid phrasing.

Her interpretations weren't always so impressive. Smither's "Love Me Like a Man" didn't come close to rivaling Bonnie Raitt's passionate rendition, and though Krall tried her best to conjure appropriately quirky and percussive atmospherics while revisiting Waits's "Temptation," in the end she merely sounded out of her element. She fared much better when evoking Allison's sardonic genius with "Stop This World" or Mitchell's poetic lyricism with "Black Crow," and nothing proved more quietly affecting than her rendition of the vintage Harry Warren-Al Dubin charmer "I'll String Along With You."

In addition to arriving with a lot of fresh or freshly arranged material, Krall was accompanied by a new trio of seasoned pros -- guitarist Anthony Wilson, bassist Robert Hurst and drummer Peter Erskine -- who added plenty of color to the performances without ever striking an intrusive note.

They also inspired Krall to occasionally improvise at the piano with more harmonic verve and swinging assurance than she's shown in the past. The concert concluded with a personal postscript, a solo recital by Krall that included a lovely and emotionally yearning performance of "Departure Bay."

Krall (shown in June) explored a variety of styles in her Merriweather Post concert.