It took no special insight to predict that the evening would be historic. Elizabeth Taylor used a night off from her own hit run in "The Little Foxes" to witness it. Fans by the score, looking as if they'd camped there for days, lined the Hall of States in quest of tickets and standing room. And the event, in the flesh, surpassed expectation. It was one of those occurrences in the art of dance that pass instantly into legend.

The occasion was predestined for glory.It was Mikhail Baryshnikov's first performance in the United States as Prince Siegfried in the complete "Swan Lake," and the first time anywhere he and ballerina Natalia Makarova were paired in this work. For Baryshnikov, now artistic director of American Ballet Theatre, and Makarova, the troupe's other most celebrated principal, the event could not have helped but recall another balletic milestone -- the night of July 27, 1974, when Baryshnikov made his U.S. debut with ABT, partnering Makarova in "Giselle." That was only months after Baryshnikov made his leap to the West, as Makarova had one four years earlier; their ABT reunion was to change the course of ballet in the West in immeasurable ways. Last night the Kennedy Center Opera House had the same feeling of unrepeatable excitement -- neither these dance artists, nor ABT nor "Swan Lake" would ever be quite the same afterwards.

It's an oddity, of course, that Baryshnikov, of all dancers, should not yet have appeared here in this ballet of ballets. The reasons are complex, and involve his reservations about conventional productions of the classic, and in particular, the treatment of the role of Siegfried. But roles, and especially traditional roles that are passed on across generations, are what dancers made of them. Now that we have the first installment of the "Baryshnikov version" of Siegfried, the part will forever assume a large new dimension.

Among other things, Baryshnikov's Siegfried puts one in mind of the parallels between "Swan Lake" and "Hamlet." The male protagonists in both tragedies are fatherless princes on the brink of manhood; both have willful, domineering mothers, and both are confronted with a malignant force in the person of a surrogate father-figure. The parallels can be carried just so far, but Baryshnikov's Siegfried decidedly takes on some of the pensive, brooding, erratically passionate attributes of the hapless Dane.

Like other interpreters of the role, Baryshnikov has inserted a solo for the Prince in Act I, which not only lends greater substance to the act but also shifts the center of dramatic gravity somewhat in Siegfried's direction. And Baryshnikov's performance of the solo, sliding imperceptibly from a ruminative walk into poetic reverie (just as Astaire used to begin so many of his dances), was assuredly one of the high points of this extraordinary evening. But even as he was amplifying the scope of Siegfried's character, Baryshnikov -- in his typically gracious and self-effacing way -- was deferring in every possible fashion to his partner. Makarova's Odette-Odile, in fact, was magnified in its radiance by Baryshnikov's so thorough and convincing submission to her spell. And when he did open up with virtuoso fireworks, as in the coruscating coda to the "Black Swan" duet, he did so only within apt dramatic bounds -- not for a second did he leave the role to score points.

Makarova, for her part, gave us a performance that has clearly been a lifetime in the making -- a model of stylistic refinement and authority raised to a new pitch of perfection through a concordance of understanding with her partner. If her physical powers, at age 40, are no longer at their peak, they are formidable still; and it matters infinitely less how many fouettes she can sustain than that her Swan Queen and evil doppelganger are dance interpretations of so high an order.

Because Baryshnikov has in mind an eventual restaging of the entire classic, the ABT "Swan Lake" is at present in a transitional phase as a whole. Baryshnikov has instituted a number of significant changes, particularly in the first three acts, to bring the ballet closer in line with the Kirov heritage that he treasures. At the moment, however, the production is a somewhat uneven compound of new features and old; the Neapolitan Dance from Act III has been dropped just in the past two days, and further modifications are doubtless imminent. Among the more notable aspects of last night's performance were the sparkling account of the revised pas de trois in Act I by Christine Spizzo, Rebecca Wright and George de la Pena, and Georgina Parkinson's debut as the Queen Mother, in an interpretation of splendidly understated hauteur.