A few days later the streamer had a video call with tennis legend Williams in which she spoke about her favourite fast food meals.
Williams also revealed her older sister Venus, a fellow Wimbledon champion, was a better tennis coach than her - as she had the patience to teach proper technique.
Mr Nye, a mechanical engineer known for hosting popular children’s TV shows about science, joined Kai at his home.
They held various scientific experiments for viewers including how an ice cube melts quicker on a metallic surface than a plastic one.
These continuous streams – colloquially known as a subathons – are usually held by streamers in an attempt to increase their number of subscribers.
This one was named Mafiathon 2 in honour of Kai’s subscribers, who he dubs the ‘Kai Mafia’.
Viewers take out subscriptions to help support their favourite streamers, with Twitch taking a cut of the money. Prices in the UK start at £4.99.
Kai already has more than 15 million subscribers and pledged that 20% of the money he has earned from this marathon effort will go towards a school he is helping build in Nigeria.
Subathons are supposed to be uninterrupted with guests standing in for Kai while he takes breaks to sleep.
However, not all went to plan with the stream having to be paused after police were called to his home following hoax reports of an emergency.