Published Thursday, 19 July 2012
Accountancy student Adam Houabi was shocked when the Take That singer popped up on ChatRoulette.com, which pairs random users from around the world in web chats.
The 19-year-old refused to believe he was chatting with a star so Williams burst into song to prove his identity.
Houabi tells The Sun: "One minute I was talking to a bloke from Algeria... then amazingly Robbie appeared. I didn't believe it was really him so he pulled his shirt down to reveal his chest tattoos and showed me five cameramen round him in his Hollywood studio.
"Then Robbie told me he was recording a new song and started singing... It was good. I liked it. I've chatted to a few strange people on Chat Roulette before but never a superstar!"