Most non-Americans don't find it too difficult to imitate an American accent, but for Rebel Wilson, there's a very easy trick to doing it - and that's pretty much just doing the opposite of what she does as an Australian. She revealed the secret on 'The Tonight Show' this week.

Rebel Wilson at the 'Pitch Perfect 3' premiereRebel Wilson at the 'Pitch Perfect 3' premiere

The 37-year-old comedienne opened up to Jimmy Fallon about how she has managed to master the American accent, despite the fact that she gets to maintain her charming Sydney twang in her new movie 'Pitch Perfect 3'.

When Jimmy Fallon asked if it's hard to go from Australian to American, she said: 'Yeah, because, for example, when I'm talking Australian I don't actually use much of my face muscles. So I'd just be like, 'Hi, how's it going?'' She barely moves her lips as she utters the Aussie greeting.

'But if I talk American, I go, 'Hi there, how are you?!'' She continues with some overly exaggerated facial contortions. 'There's a lot more face muscles.'

But it was her onscreen father John Lithgow who had to work on his voice in 'Pitch Perfect 3'. He's a New York guy, but he's got the British accent down given that he went to the London Academy of Music and Dramatic Art. Australian, on the other hand, posed a bit of a challenge.

'He had to do my Australian accent which is actually very difficult to try to replicate', Rebel said. 'He only had three days to learn my accent'.

Whether John Lithgow had any tricks up his sleeves to keep his Aussie accent going, we are yet to find out, but even Rebel let slip that he 'probably' won't win an Academy Award for the role. 

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'Pitch Perfect 3', directed by Trish Sie, is set to hit US theatres tomorrow (December 22nd 2017).