Mark Zuckerberg has been filmed pouring a bucket of iced water over his head in the latest viral Facebook challenge - and then nominated Bill Gates to do the same.
The Ice Bucket Challenge is the latest social media craze celebrities have taken to in a bid to raise money for neurodegenerative disease ALS.
US President Barack Obama has been nominated for the stunt but opted to donate to the charity instead.
The video, posted on Zuckerberg's Facebook page, sees the billionaire entrepreneur accept his challenge set by Governor of New Jersey Chris Christie.
The 30-year-old founder of Facebook said: "I'm going to challenge Bill Gates, my partner at Facebook Sheryl Sandberg and Netflix founder and CEO Reed Hastings," before pouring the freezing water over his head.
The Ice Bucket Challenge has been adopted by Macmillan Cancer support in the UK, with celebrities including tennis star Andy Murray and golfer Ian Poulter taking part.