Gilbert and Sullivan were a team for 20 years, but their partnership was like a rocky marriage -- sometimes harmonious, often adversarial and occasionally downright hostile.

In "Sullivan and Gilbert," playwright Ken Ludwig turns their incompatibility into an evening of comedy. The play takes us backstage at the Savoy Theatre for an eventful day in the life of Victorian England's most famous composer and librettist.

Ludwig's 1989 play, which opened last weekend at the Dean Lesher Regional Center for the Arts in a new production by the Diablo Light Opera Company, portrays Gilbert and Sullivan at a point toward the end of their illustrious careers, after the success of such operettas as "The Mikado," "Iolanthe," "HMS Pinafore" and "The Pirates of Penzance."

It's 1890, and the Savoyards are preparing a special revue performance for Queen Victoria. All is not well backstage -- Sullivan (Marion Russon) has been ill and has missed most of the rehearsals. Gilbert (Michael Manley) is trying to break in a new soprano (Alicia von Kugelgen as Violet Russell) in time for the show, which is set to open in about eight hours.

To make things worse, Sullivan has invited Alfred, Duke of Edinburgh (Michael McCarty) to join the cast. The bumbling duke can't wait to get onstage, even though he can't sing, dance, or remember his cues. When Gilbert finds out, he's furious.

With a company of temperamental actors to manage, and their longtime producer, D'Oyly Carte (Bill Frey) breathing down their necks, there's plenty for the two men to fight about. But the play hinges on another issue. In the first scene, Sullivan tells Gilbert he's in love -- but he won't say with whom. Gilbert is determined to discover the lady's identity, and Sullivan vows to keep it a secret.

Like the recent Mike Leigh film, "Topsy Turvy," the play takes full dramatic advantage of the differences between Gilbert and Sullivan. Librettist Gilbert, for example, was happy to write "entertainments"; composer Sullivan has his sights set on serious music. Gilbert was a rigid perfectionist, Sullivan an incorrigible romantic. Sullivan had been knighted, an honor Gilbert coveted, but didn't receive until years later.

In one scene, they even bicker over the number of works they've co-written. "Eleven," says Sullivan. "Twelve," Gilbert insists.

But the best thing about the play is the way it incorporates Gilbert and Sullivan's music. There are over 15 songs included, and the cast, under the direction of Sue Ellen Nelsen, performs them with style and panache.

As he did in his other backstage comedy, "Lend Me a Tenor" (which will open next month as a Role Players production in Danville), Ludwig has created clearly delineated characters, and the actors do a fine job of bringing them to life. Manley and Russon make the audience feel the genuine affection under all the hostility. Sharon Specher's level-headed Kitty Gilbert, Frey's harried D'Oyly Carte, and McCarty's dim-bulb Alfred offer strong support.

T.J. Burnie's Jesse, Judy Ryken's Sybil, Jay Krohnengold's George and von Kugelgen's Violet are the standouts among the singers. Matthew Ballin's Durward, Stuart Berg's Rutland, Christine Macomber's Rosina and Robin Taylor's Cortice round out the able cast.

Alexander Katsman leads a small ensemble in the pit, and the musical numbers -- including "If You Go In," "Three Little Maids from School," "Never Mind the Why and Wherefore" and "I Know a Youth Who Loves a Little Maid" are colorfully performed.

Nelsen's staging keeps the 2 hour, 35-minute show moving, although the first act, which clocks in at 90 minutes, feels as if it could use a little trimming. Still, Ludwig's play is a fine choice for the Diablo Light Opera Company, which started with Gilbert and Sullivan 41 years ago. For fans of the duo's music, "Sullivan and Gilbert" is a must-see.