Being mistaken for a celebrity can't be all bad, but when you are an actress mistaken for a more famous star, it can get pretty awkward. That's what happened to Isla Fisher when she met Lady GaGa, who seemed certain that she was in fact Amy Adams

Isla Fisher at the ITV StudiosIsla Fisher at the ITV Studios

41-year-old Isla Fisher has never and will never be Amy Adams, but when she bumped into Lady Gaga at the 2014 Vanity Fair Oscar party, she was determined to pretend that she was the 'Arrival' star after the singer got the two of them mixed up.

'I was there all excited and dressed up at the bar and schmoozing with show-biz types, and the crowds parted and there was Lady Gaga', she said on 'Jimmy Kimmel Live'. 'She's heading right towards me and she says, 'Thank you. Your performance in American Hustle, Amy, was...''

'It's Lady Gaga. I love her so much, I [didn't] want to tell her the truth. So I just gracefully thanked her [and] bowed my head', she continued. 'Then she wants to talk about the performance and now I'm thinking, 'I don't wanna be a liar'. I look over her shoulder and there's Amy Adams walking into the party!'

And if you thought the game was up at that moment, you'd be wrong because Isla had the perfect save. 'I'm like, 'There's Isla Fisher'', she said. 'I said, 'She's not even nominated for anything, what's she doing here?''

More: Isla Fisher puts Amy Adams' face on her Christmas card

It's certainly not the first time Isla - who is set to appear in the forthcoming Keanu Reeves movie 'The Starling' - has confused the public with her resemblance to Amy. She once decided to breastfeed her child during a shopping trip to Ikea, when she was stopped by a mother who asked her to sing the song 'That's How You Know' from Amy's movie 'Enchanted'. 

Tone-deaf Isla happily obliged leaving the Amy fan to realise her mistake with horror.