The New York City Ballet showed its depth Saturday as continued illnesses and injuries caused a dizzying number of both cast and ballet shuffles. When Maria Calegari, scheduled to fill in for the injured Merrill Ashley in Jerome Robbins' "Concertino," became injured herself, the entire ballet was pulled and Balanchine's "Tschaikovsky Pas de Deux" substituted, changing the complexion of the "All Stravinsky" matinee. Calegari's injury also posed a problem for a Robbins work, "The Four Seasons," scheduled for the evening's National Endowment for the Arts gala performance, and Valentina Kozlova and Leonid Kozlov interrupted "On Your Toes" rehearsals to fly in and save the day.

Such is the strength of the company that none of the substitutions was of inferior quality. Who else could nonchalantly slip in "The Four Temperaments" when Ashley's injury made a performance of "Square Dance" impossible, as NYCB was forced to do for a second time Saturday evening? Among the dancers, Kyra Nichols has been the season's trooper, substituting for Ashley in several roles and dancing the hastily scheduled "Tschaikovsky Pas de Deux" with her special combination of daring and sweet clarity.

Of the expected cast changes, the most notable was Sean Lavery's Washington debut at the matinee in the title role of "Apollo," one of Balanchine's most important roles for men. Lavery, new to the part, was at times too elegant and tentative, but exhibited a few brash, bold and sporty moments in his solos, around which he could build a very individual interpretation. As his muse Terpsichore, Heather Watts danced superbly with a flirtatious manner that gave spark to the performance.

Both flirtatiousness and sparkle were missing from Balanchine's "Capriccio for Piano and Orchestra" (a k a "Rubies"). Ib Andersen, one of the company's outstanding virtuosi, was surprisingly subdued in this show-off role. Balanchine's "Symphony in Three Movements," which closed the matinee, was danced with all the bite and power one could wish.

Alexandre Proia made his local debut Saturday evening as the lover in Robbins' new "In Memory Of . . ." exhibiting an arresting stage presence and strong, subtle partnering in what is, essentially, a partnering role.

In "The Four Seasons," Miriam Mahdaviani was fresh and spirited as the shivering leader of the "Winter" section and Michael Byars, a young corps dancer with an exceptionally springy jump, was the mischievous Fawn of "Fall."