Actress Keira Knightley has opened up about her party trick.

Knightley, who is currently adhering to self-quarantine guidelines as the world combats COVID-19, revealed it while taking part in World Health Day's Hope From Home livestream, reports dailymail.co.uk.

Introducing herself on the event's social media livestream, she told viewers: "Hello, I'm Keira Knightley and I am here for Hope from Home on World Health Day.

"I made a little sign, and I was trying to think of something entertaining to do and I couldn't think of anything so I'm going to play my teeth, which is my one and only party trick."

The British star proceeded to tap out the melody to "Yesterday", a 1965 hit for The Beatles.

Finishing her party trick, she added: "Thank you all for watching. Thank you to all the frontline workers and medical teams who are working so hard right now. If you want to donate, that would be great."

She had previously shown off the skill while appearing on a show in 2019.

Using her fingers to tap the melody to "Raindrops keep falling on my head" and Luis Fonsi's "Despacito", she had said: "There was a boy at school when I was about seven or eight and he went on a talent show on TV, so he was like the coolest person ever, and he played his teeth.

"So, everybody at my school was like, that's cool, so everybody from that school can probably play their teeth."