Roberts, 38, was chosen for the play last year with producers hoping her cinema box office magic will draw big audiences to the Bernard B. Jacobs theatre in New York.

Tuesday evening's performance marks the beginning of "previews" for the play with the official opening set for April 19.

"Three Days of Rain," which was produced Off-Broadway at the Manhattan Theatre Club in 1997, is played out in two acts. In the first act, Roberts plays a daughter who, along with her brother, tries to unravel the truth behind her father's death. In the second act set 30 years earlier, Roberts plays the daughter's mother.

With little experience on stage, the star of "Pretty Woman" admits to being nervous about her theatrical plunge.

"By the time I get there, I'll be entirely apoplectic," Roberts told the New York Times last year. "But the terror is part of the excitement."

The playwright said Roberts' Hollywood stardom has had no disruptive effect on preparations for the play.

"Rehearsals have been amazingly normal," Greenberg told the daily USA Today.

Roberts, who won an Oscar in 2000 for her leading in role in "Erin Brockovich," went on maternity leave in early 2005 to take care of her twin children and the play marks her return to work. She is also reportedly in final talks for work on a new film entitled "Daniel Isn't Talking."