By Zorianna Kit

LOS ANGELES (Reuters) - Actress Rachel Weisz, who won a best supporting actress Oscar in 2006 for her role as Tessa Quayle in "The Constant Gardener," takes on her most action-packed part to date when she stars opposite Jeremy Renner in "The Bourne Legacy," opening on Friday

Weisz plays scientist Dr. Marta Shearing, who goes on the run with Renner's character. But the British actress is better known for her dramatic roles.

Weisz, 42, talked with Reuters about shooting her motorcycle action sequence in the "The Bourne Legacy" and also about playing Evanora, the Wicked Witch of the East in Sam Raimi's "Oz: The Great and Powerful," due out next year.

Q: In "The Bourne Legacy," Dr. Shearing starts off as a victim and then ends up kicking some serious butt by the end of the movie. How did you like partaking in all that action?

A: "I didn't think of myself as being bad-ass. I was just thinking of my character fighting for her life. If I was in that situation, I think I would do the same thing."

Q: Did you have to go through any extensive fight training?

A: "I didn't have to go through any training. My character is not a superhero so I didn't need any special skills or muscles. My character had to run, so I did a lot of interval training on the treadmill to make sure my lungs were okay."

Q: There is a quite an intense motorcycle sequence that was shot in Manila with you and Jeremy Renner on a single motorbike. Was that you or a stunt double?

A: "That was me doing it. We did a little practicing on the bike, but mainly we just did it. Every rehearsal was captured on film and they pieced together the best bits from each take. I had to do it 40, 50 times, so I was learning in the moment."

Q: Your character is a scientist. Did you visit any real life scientists for research?

A: "I met a woman who was a scientist and thought, 'Oh, she's just a human being like me. I could pretend to be her.' Then I had the job of understanding the science. That took a while because I'm not a scientist. I had to Google a lot of (terminology). I just had to really understand what it was I was saying. That took time alone in a room saying it over and over again until I understood it."

Q: Was the shooting schedule pretty grueling?

A: "It was pretty grueling. My character goes through a lot of stuff. Everyone gets murdered at her workplace, the FBI tries to kill her, then she burns down her house and goes on the run. Not a bundle of laughs!"

Q: Most of your scenes are with Jeremy. What was it like working with him?

A: "Jeremy and I work in a very similar way. We don't like to analyze and talk about the scene before we do it. We never rehearsed, not for one second. We'd just come to do the scene, turn the cameras on and start doing it. We're coming from exactly the same place."

Q: It must have been nice to take a break from the shoot and do something completely different and fantastical like playing witch Evanora in "Oz."

A: "'Bourne' is a particular brand of action. It's realistic. It looks and feels real. ('Oz') was a very, very different (type of) acting. The film is complete fantasy. I couldn't do any research. I couldn't meet any witches and go fly!"

(Reporting By Zorianna Kit, editing by Jill Serjeant and David Gregorio)