It was a match typifying the new regime at American Ballet Theatre, as company director and "superstar" Mikhail Baryshnikov partnered youthful soloist Cynthia Harvey last night in a performance ending the "Swan Lake" marathon which began last Friday. The occasion was a "second" for both artists: Baryshnikov had performed his first Prince Siegfried in America only this past Sunday evening in the current ABT run at Kennedy Center, opposite Natalia Makarova; earlier the same day, Harvey danced his first Odette-Odile ever, with Ross Streton as the Prince.

Inevitably, Baryshnikov's profound conception of his role again dominated the proceedings. When, for example, at the end of his first-act solo, he divines that his newly acquired crossbow is somehow the instrument of his destiny, and then, swinging it excitedly, spurs himself into an exalted blur of turns, we know we are in the presence of a sublime dance imagination. Yet, for Baryshnikov, this was on the whole a restrained performance. If he deferred to Makarova, who, at 40, is seven years his senior, he took even greater care not to overpower Harvey, who is 10 years his junior and a newcome to "Swan Lake" to boot.

Inevitably, too, the disparity in artistic level could not be hidden. On the other hand, Harvey, having undergone the fiery baptism of a first try, unquestionably garnered new assurance and freedom from Baryshnikov's solid, sympathetic support. The gains were most apparent in the "Black Swan" duet and the melancholy fourth act. Elsewhere, the role still seems largely unassimilated, insofar as characterization is concerned. Harvey's promise is ample, but it's much too early to tell whether the requisite depth will materialize or not.

Other aspects of the performace last night were far from perfection, as the company continues to struggle with the transition from the former production to the current, partially revised version. The pas de trois of Act I, despite some felicities from Kristine Elliott and Leslie Browne (if none at all from Dennis Marshall) was pretty limp, and the new Act III divertissements looked as disheveled as the old ones used to. It's clear ABT's "new" "Swan Lake" will still be a long while in the making. In the meantime, Baryshnikov's Siegfried can do much to tide things over.