Natalie Portman won the best actress Academy Award on Sunday for her role as an unhinged ballerina in "Black Swan."

The 29-year-old Israeli-American was considered the strong favorite for the award, having dominated the various awards shows leading up to the Oscars.

Portman trained five hours a day for six months to prepare for "Black Swan," a project she and director Darren Aronofsky first discussed about nine years ago. When they started shooting the film in 2009, it had not secured any financing.

Her character, desperately insecure and possibly still a virgin, contends with professional jealousies and rivalries as she secures the dual lead roles in "Swan Lake."

The film was a commercial and critical hit, with worldwide ticket sales of more than $200 million. As a bonus, Portman last year announced she was pregnant and would marry the baby's father, a dancer she met on the "Black Swan" set. She previously received an Oscar nomination in 2005, for her supporting role in "Closer."

Portman's rivals were four-time nominee Annette Bening for "The Kids Are All Right," previous Oscar winner Nicole Kidman for "Rabbit Hole," Jennifer Lawrence for "Winter's Bone," and Michelle Williams for "Blue Valentine."