Playwright Arthur Kopit learned a very important lesson on his way to producing his interpretation of Gaston Leroux's classic novel The Phantom of the Opera (Sunday and Monday at 8 p.m., Ch. 2):

"Do not write a musical that competes with Andrew Lloyd Webber."Kopit was speaking to television critics in Los Angeles during the network press tour, trying to convince them that he really, truly came up with the idea for his "Phantom" before Lloyd Webber made theatrical history with his megahit musicalization of the same story.

Well, OK - at least at about the same time.

Kopit's idea was different than Lloyd Webber's.

"It's a terrific story, one that captures audience imagination in a very particular way," Kopit said, "but I remembered it as being better than it had ever been done before. The previous versions (including the 1925 silent classic starring Lon Chaney and three subsequent remakes) focused on the horror of the story rather than the romance. And none of them helped us understand how the relationship started. I knew that in order to tell the whole story I had to start earlier than just when the Phantom meets Christine."

So Kopit came up with a script in which the Phantom is a romantic hero, frightening only to those who would misuse the opera house wherein he dwells - and to those who would stand in the way of Christine's eventual rise to stardom. And he decided to use plenty of music in his storytelling - not original music, but classical opera arias that would imbue his production with a sense of the Phantom's heart, soul and passion.

Unfortunately for Kopit, Lloyd Webber came along with a similarly romantic approach and a captivating original score that made everything else theatrical at the time look like small potatoes - especially anything else based on "The Phantom of the Opera."

"It was devastating," Kopit recalled. "Here was work that I deeply loved, and it looked for all that world like it would never be seen."

That's where NBC enters the picture. Kopit heard that the network was in the market for a miniseries, so he sent them a copy of his script.

"I had to convince them that I wasn't following on the heels of Lloyd Webber's success," he said, echoing a refrain he has doubtless repeated many times in the past couple of years. "But once I was able to do that, it wasn't difficult to help them see the potential of this interesting, unusual love story."

In fact, NBC's decision to go ahead with Kopit's "Phantom" may owe as much to the cult hit status of CBS's "Beauty and the Beast" on TV as it does to the success of Lloyd Webber's theatrical "Phantom." It is a similar kind of elegant fantasy, with beautiful words and gorgeous music wrapped gently around a timeless story of unrequited love.

Kopit's "Phantom" introduces viewers to Eric (played by Charles Dance), the Vincent of the tunnels underneath the Paris Opera House. Eric has lived there all of his life, supported to a great degree by Opera House manager Gerard Carriere (Burt Lancaster). But now a new owner (Ian Richardson) has come to take over the facility, and he and his overbearing wife, Carlotta (Andrea Ferreol), are determined to rid the theater of this pest they call "The Phantom of the Opera."

But even though Eric is concerned about what they are doing to the Opera House, he is even more pre-occupied with Christine (Teri Polo), a winsome costume mistress who has the voice of an angel. The two meet (not by chance, as you might expect), and under Eric's tutelage Christine's career is launched - inauspiciously, as it turns out, thanks to Carlotta.

As you might expect, the relationship has some rough spots to negotiate during the four hours Kopit takes to tell his story, such as when Christine faints when Eric finally complies with her pleading to let her see what's beneath his mask (a harsh reality viewers are thankfully spared). But there are also some incredibly romantic moments - none moreso than when the two sing together (she onstage, he in his familiar Box No. 5) in a duet from "Faust."

Kopit's script maintains his vision throughout, expertly mixing moods ranging from the ridiculous ("I'm not used to killing people," says the Phantom after a rare violent episode. "It throws me off.") to the sublime. And the production values throughout are first rate, with the Phantom's underground labyrinth and the expected crashing chandelier effect especially effective.

Dance, who viewers may remember from his work in "The Jewel in the Crown," is a superb Phantom - brooding and mysterious, and yet somehow approachable. Polo makes the most of her big TV break, creating a flesh and blood heroine who is utterly believable, with subtle intonation, looks and gestures that communicate the emotional essence of Kopit's words.

The rest of the cast is similarly effective, especially Ferreol who practically steals the show with her broad comic Carlotta. That she isn't able to steal focus is a tribute to the strength of the miniseries.

But then, so is the very existence of Kopit's "Phantom," the TV special that refused to be intimidated by a Broadway success.