Veronika Part and Diana Vishneva each trained at the Vaganova Academy in St. Petersburg, joined the Kirov Ballet in the mid-1990s, and immediately became leading dancers in the company. Each now dances with American Ballet Theatre, and each danced an exciting Odette/Odille in ABT’s “Swan Lake”on Wednesday.And there the similarity between the two ends.

Ms. Part’s natural realm is the adagio, while Ms. Vishneva is the most exceptional allegro technician the Kirov had produced in a long time.Ms.Part is lush; Ms. Vishneva is chiseled and wiry. Ms. Part retains a visible connection to the classic Kirov aesthetic tradition, whereas Ms.Vishneva’s aptitude for neo-classical and modern ballet idioms represents a real break from the past.

Ms. Part’s performance Wednesday afternoon seemed like a rebuke to the critics who have carped about her alleged technical weakness. In a way, she approached the performance from a classically American viewpoint, concentrating on technical integrity and cleanliness of execution. Ms. Part is now as thin as when I first saw her dance in 1999. But she is still very tall, big-boned, curvaceous, and rather broad-shouldered: Her great white goddess in “Swan Lake”recalls ABT’s Cynthia Gregory and Martine van Hamel.

In the white swan Adagio, Ms. Part used the sight lines and axial dimensions of her gorgeously long, sculptural silhouette to establish emotional contact with her Prince Siegfried, Marcelo Gomes. There was a palpable vibrato to her movement that seemed capable of sustaining a story line all by itself. Her performance suggested an instrumental tone poem at times, and was less thrilling emotionally than in either of the previous two years. At times, she seemed to be shutting Mr. Gomes out of the story. But part of what makes theirs a great partnership is his willingness to support any interpretative direction she embarks on.

As the black swan Odile, Ms. Part was a soft-spoken grande dame; her performance seemed somewhat in the manner of her teacher, the late Inna Zubkovskaya. I’ve never seen Ms. Part dance the black swan variation anywhere near as well as she did Wednesday afternoon. The problems with weight shifting that had discombobulated her in the past were all smoothed out.What a pleasure it was to watch her perform the single fouettes in the coda with such aplomb – no shoulders hunched, none of the chin jutting that often besets ballerinas when they fouette themselves into a tizzy.

Mr. Gomes had some difficulty in past weeks with the slow continuity needed for his solos as Lescaut in “Manon” and Von Rothbart in “Swan Lake,” but Wednesday afternoon he was back at the top of his game. He gave a gloriously committed, intense performance, technically assured at every point on the dynamic spectrum.

Last September, I saw Ms. Vishneva dance her first Odette/Odile with the Kirov at the company’s season opening in St. Petersburg. That was a great performance, but she fared less well on Wednesday evening.

Ms. Vishneva, who is not a naturalborn Odette/Odille, danced Kenneth MacMillan’s expressionist “Manon” five days earlier, and it would be impossible to expect her to smoothly shift gears immediately.Furthermore,she has danced all over the world with several companies in the past year, and the exertion may have taken its toll.

Although technically she hit every target at her first “Giselle” two weeks ago, her muscular condition seemed exhausted. The arch in her back – one of the special hallmarks of a Russian ballerina – was gone, and the stylistic eloquence of her arabesques was limited. Her back and arabesque were more limber in “Swan Lake,” however. She only seemed fatigued at odd moments when her epaulement became careless.

Ms. Vishneva radiates mental alertness onstage, and she may be too imaginative to easily attain an ideally integrated characterization of Odette/Odille. Though her “Swan Lake” performance was schismatic, it was also riveting and electric.

Most impressively, the controlling metaphor during Ms. Vishneva’s performance in the first lakeside act was a trapped and traumatized bird. She recoiled unequivocally from the prince during their first two encounters, beginning to thaw only during the adagio, where her tempo was faster than Ms. Part’s and her movement more clipped, but not objectionably so. Toward the end of the adagio, however, she soared into moments of baroque abandon, while in her variation she seemed more like a plaintive young girl. In the coda, her arms became wings beating frantically against the bars of an invisible cage.

As the black swan, Ms. Vishneva skipped exuberantly down the palace stairs; throughout the act, she took unabashed delight in her gambit of deceit and seduction. She produced regal arabesques, whether lifted in the arms of her Prince Siegfried, Jose Manuel Carreno, or standing alone on pointe, but more often she was a flirtatious, gaily immoral troublemaker.

More than Ms. Part, Ms. Vishneva made a complete transformation from black swan back to white during the duplicitous diagonal in the Adagio, encompassing dime-stop transitions back to Odile’s persona as she monitored the prince’s credulity. In her variation, she interjected two jetes into her manege of pique turns – where did she find the strength? – that were so startling and powerful they overcame my reservations about international stars bringing their own choreography.

As he did last week opposite Julie Kent in “Manon,” Mr. Carreno made his performance much more than the sum of his smile and his beautiful pirouettes. In the past, when the queen mother has informed Mr. Carreno’s Siegfried that he must now find a bride forthwith, he has responded with an almost infantile acquiescence. But on Wednesday night, he reacted as a mature patrician, registering the full onus of her decision and what it meant for him.

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ABT’s Irina Dvorovenko had more of a vacation during last week’s run of “Manon” than I imagined when I wrote the review that appeared in this space two days ago. It was not Irina but her mother, Olga Dvorovenko, who portrayed the bordello owner at the performance I attended on June 20.

American Ballet Theatre’s Metropolitan Opera season runs until July 15 (Lincoln Center, 212-362-6000).