Kristina Sullivan makes an utterly loverly Eliza Doolittle; Luther Chakurian, a persuasive, if somewhat unorthodox, Henry Higgins.

Add the indisputable genius of Alan Jay Lerner’s book and lyrics and Frederick Loewe’s score.

And that’s pretty much the ball game in Masquerade Theatre’s current production of My Fair Lady.

It’s not that other elements are unimportant — just that, with material of this caliber and a show so intently focused on the evolving relationship of the two leads, it’s the realization of those roles and the effective delivery of their songs and scenes that qualifies any staging of this beloved classic as either a success or failure.

One of the greatest theatrical triumphs of the 20th century, the musical based on George Bernard Shaw’s Pygmalion established itself as the ne plus ultra of musical theater artistry upon its premiere in 1956. More than a half century later, it still holds up extraordinarily well. Indeed, its enchanting music, witty lyrics and superbly crafted book put most current Broadway champs to shame.

Other greats, including talents as mighty as Rodgers and Hammerstein, had considered the source and decided it simply would not adapt to the musical stage — chiefly because there’s only the slightest trace of subliminal romance in Shaw’s tale of the fastidious phonetics professor who wagers he can transform a bedraggled Cockney flower girl into a proper lady by teaching her to speak properly.

But Lerner and Loewe found the ideal means of retaining everything essential in Shaw’s play, including its literate tone and philosophical point, while injecting the spark of musical comedy charm, sentiment and bigger emotions. It’s hard to think of a play-to-musical adaptation more inspired in its choices of which scenes to keep pretty much intact, which to transform into musical numbers and where to add new narrative content, such as the sequence showing Higgins actually teaching Eliza.

Sullivan charts Eliza’s progression with passion and convincing detail, from squawking guttersnipe to self-possessed woman. Along with Eliza’s warmth and humor, Sullivan conveys her determination and instinctive logic. She sings Eliza’s succession of great numbers beautifully, from the wistful Wouldn’t It Be Loverly? to the enraptured I Could Have Danced All Night, to the fiery Show Me.

Cast somewhat against type, Chakurian adapts his big-baritone leading man style to create a fastidious, persistent, quietly commanding Higgins — a misogynistic loner who discovers his own emotional vulnerability. Chakurian capably delivers such intricate patter songs as An Ordinary Man and A Hymn to Him, but also brings more voice than the usual talk-sing approach, especially in his poignant apotheosis I’ve Grown Accustomed to Her Face.

Dominic Abney makes a raffish, crusty, gravel-voiced Alfred P Doolittle, Eliza’s incorrigible father. Adam W. Delka is droll and durable as unflappable Colonel Pickering. As Eliza’s ardent suitor Freddy, Cole Ryden has the right lovestruck look and the soaring tenor to sell On the Street Where You Live. Allison Sumrall bring wry point to her scenes as Higgins’ disapproving mother.

Director Phillip Duggins has staged the show in his usual straightforward, traditional fashion, better than usual at not letting book scenes turn sluggish. Laura Babbitt and Michelle Macicek’s choreography is predictable but lively, the usual rowdy-Cockneys-whooping-it-up antics. Sets and costumes are serviceable if far from sumptuous. Dominique Royem conducts with spirit, though it takes a few scenes for the ear to adjust to the streamlined orchestral forces (considerably diminished from the original orchestrations), as well as to the aggressive amplification.

Still, little else matters when Sullivan’s Eliza and Chakurian’s Higgins square off, and especially whenever they sing those irresistible songs.

MY FAIR LADY
7:30 p.m. Friday-Saturday, 2 p.m. Sunday
Zilkha Hall, Hobby Center, 800 Bagby
Tickets: $26-$66; 713-868-9696