It would seem impossible to pump any new life into a song as overworked as Stephen Sondheim's "Send In The Clowns" but last night at the Merriweather Post Pavilion, jazz singer Sara Vaughan transformed the song into riveting musical drama. Vaughan stretched each note until she had voiced every possible tonal and emotional nuance. She seemingly held the final lung-defying phrase long enough to bring her to the brink of an emotional breakdown.

Working with her own trio and the Henry Mancini Orchestra, Vaughan turned the whole set of familiar standards into one vocal tour de force after another. She accelerated the tempo on "Fascinating Rhythm" until she was ripping through scat syllables at machine-gun speed. But more often she threw away the crutch of fast momentum. She would improvise at slow tempos where each note and each shift had to be that much more original, that much more perfect. Each one was.

The second set, when Henry Mancini took over his 42-piece orchestra, proved anticlimactic. Mancini is a talented pop composer, but last night his arrangements and piano playing were lackluster. Mancini's TV themes and movie chase music were smothered by faceless string and horn charts. His real talent only emerged when Saran Vaughan came back and lit up his classic standard, "Moon River."

Sarah Vaughan will sing at the Wolf Trap Jazz Festival July 2.