An occasional update of New York theater openings
* VALLEY SONG
(Manhattan Theatre Club at City Center): Athol Fugard's first post-apartheid play, in a production starring the author himself. He plays two roles: ''The Author, a White Man,'' and Abraham Jonkers, an elderly black farmer who tries to prevent his 17-year-old granddaughter (Lisa Gay Hamilton) from leaving their rural valley to study music in Johannesburg. The play traffics in familiar themes and is overly reliant on symbolism. While it is not one of Fugard's strongest works, it does contain moments of intense beauty, and he skillfully examines the soul of his characters.
* MOLLY SWEENEY
(Criterion Center - Laura Pels Theatre): American premiere of Brian Friel's three character play, produced by Roundabout Theatre Co. and starring Catherine Byrne, Jason Robards, and Alfred Molina. Byrne plays the title role, a middle-aged woman who has been blind since infancy. Molina is her husband, a self-proclaimed intellectual whose pursuits have ranged from the study of philosophy to goat farming, and Robards is her doctor, an alcoholic who is seeking to restore his reputation by performing an operation he is sure will restore Molly's sight. The story is told entirely through fragmented, interconnected monologues, and the results are more than a bit static and talky. Still, the playwright who wrote ''Dancing at Lughnasa'' and ''Translations'' has a gift for language that soars, and the piece is brilliantly acted.
* SHEILA'S DAY
(New Victory Theatre): The current presentation in 42nd Street's gorgeously restored New Victory Theatre is a piece written by Duma Ndlovu and Mbongeni Ngema, the creators of such works as ''Sarafina!'' and ''Woza Albert!'' This production from New Jersey's Crossroads Theatre Company deals with the common and parallel struggles of South African and African-American women, and tells its stories through an exuberant combination of music (blues, gospel, even Zulu chants), dance, and text.