It is an actor's fantasy: The phone rings and a television production company offers you the lead role in a new film, a meaty role most actors would kill for. The part is yours for the asking -- no auditions or politicking necessary. Impossible? That's what happened to Alfre Woodard, who plays Winnie Mandela to Danny Glover's Nelson Mandela in HBO Pictures' "Mandela," premiering tonight at 8 on the pay TV service.

"The liberation struggle in South Africa has been a top priority in my thoughts and political feeling for the past five years," said Woodard. "Not only does Mrs. Mandela mean so much to me, but I felt a responsibility, saw the film as a place for me to help out, to marry my art and my social conscience, which is what artists in other societies have always done."

Alfre Woodard, native of Oklahoma, graduate of Boston University and resident of Hollywood, Calif., has a face like putty, a voice that works the nuances of language like James Brown works a lyric, and great, almond-shaped, liquid eyes that project, depending on the moment, all the world's joys, sorrows or lustful feelings.

Woodard, 34, is no newcomer to television. She has played the role of Dr. Turner on NBC's "St. Elsewhere," and is up for an Emmy this week for her portrayal of a fighter for the rights of Vietnam veterans in "Unnatural Causes." She is now filming "The Fierce Dreams of Jackie Watson" for NBC.

She was nominated for an Oscar for best supporting actress in "Cross Creek" and has already won an Emmy, for her appearance on "Hill Street Blues."

If there are any doubts about Woodard's range as an actress, her performance in "Mandela" should put them to rest. As Winnie Mandela, Woodard's performance is rife with emotions: She is tender, steely, full of joyful laughter and black, hot anger. Her performance not only brings Winnie Mandela the person to life, but also maps the evolution of a private woman into an outspoken and internationally known public persona.

"Mandela" begins in 1948 with the organization of the Defiance Campaign, a non-violent act of resistance against the apartheid government's law requiring indigenous South Africans to carry pass books. The campaign is started by the African National Congress (ANC), South Africa's leading liberation organization.

"Mandela" covers the banning of the ANC by the Afrikaner government, the massacre at Sharpeville of at least 69 South Africans, and the violence of the Soweto demonstrations in 1976. The political history of the last 40 years is told through the lives of the Mandelas and their close associates. "Mandela" ends in 1985 with Nelson Mandela about to mark his third decade in prison and his wife having grown from a shy young woman in love with a public man to a public person in her own right.

Woodard avoids the holier-than-thou attitude that so often afflicts fictional productions about real people, particularly women. In Woodard's hands, Winnie Mandela comes alive, not only as a remarkable woman, but as a living, breathing, loving one -- no saint, but a good woman transformed into a great one by the conditions in which she lives.

Not coincidentally, many of the roles Woodard has played are women of a quiet, fierce independence, regular women made greater by their times and circumstance.

"I felt less personally emotionally involved in this role, for once," said Woodard with a giddy laugh. "Usually, an actor brings her interpretation, but with a woman like Mrs. Mandela, we have not seen her, we do not know her. There's the occasional newsreel, and there we see her as the 'Mother of the Nation,' with no sense of what she went through to become that. So I felt compelled, more than ever, to actually bring the person, the woman, to the screen, to try to give her a voice."

In addition to giving shape to its principal characters, "Mandela" may do as much, if not more, for Americans' understanding of the issues in South Africa than a year of "Nightline" and news reports.

"At first, I thought the script was too simplistic," admitted Woodard, "until I started saying to friends, intelligent, university-educated people, 'I'm going to play Winnie Mandela,' and they'd say, 'Uh, who is she, I think I've heard of her ...'" Woodard recalled with a chuckle. "In doing this film, I hoped to put a face on Winnie Mandela. And I realized the film couldn't be too simple: Most people know so little."

"Mandela" was filmed in Zimbabwe, a nation that borders South Africa and is very much like it in terms of history, geography and political struggle. After years of nonviolent and then violent warfare, Zimbabwe gained its liberation in 1980.

Woodard described the eight weeks in Zimbabwe as "a fantastic experience. It is a new country, and there is this spanking newness, the hope of a new country, and I'd never seen that before. It was also," she laughed, "one of the friendliest places I've ever been."

Does Woodard think her work in "Mandela" will provide a boost for her already rising star? "I don't know," she said thoughtfully. "I sort of defy a lot of the rules. In my career, things that I do don't necessarily add to or subtract from what I'm doing. I just go on and find the next project or person to create with."

And what does she hope becomes of the film? "If everything disappears, it is forever a record that these people existed and what they struggled for," she said seriously, adding: "Hopefully, 'Mandela' will be shown at a great big film festival in a free South Africa, someday."