Mia Wasikowska found acting in 'Alice in Wonderland' tough.

The 20-year-old actress - who plays the lead role of Alice in the Tim Burton-directed movie, which takes place when Alice is a teenager, years after the setting of the original Lewis Carroll book - admits the green screen effects used in the film made the cast's job hard.

She said: "When you're acting with another person, you're bouncing off their energy and you're helping each other.

"When you're acting with a tennis ball that is supposed to be the Cheshire Cat, you don't know what the Cheshire Cat is giving you, so you're having to pretend you know.

"It really meant a leap of faith, and having to trust Tim when he says things like, "Be a bit more angry with it.' But it's hard, because you're really filming in a void."

However, she claims working with luminaries such as Johnny Depp, Helena Bonham Carter and Anne Hathaway, who play the Mad Hatter the Red Queen and the White Queen respectively in the movie, helped her learn how to be a better actress.

She told the Sunday Times newspaper: "I felt like it was acting school, working with all these people. They make really brave choices.

"They showed me that, as an actor, you have to be prepared to do things that you could completely mess up, or that people may not like. But it's much more interesting playing a character that's not instantly likeable."

'Alice in Wonderland' is released in the UK and US on March 5.