After a rocky introduction, Justin Bieber made a new friend in Rolling Stones guitarist Keith Richards -- get the details on their encounter in the new issue of Us Weekly Credit: Allen Berezovsky/Getty Images; Dave J Hogan/Getty Images

Way to romance the Stone, bro. Justin Bieber made a very famous new friend in Rolling Stones guitarist Keith Richards recently, but as insiders reveal in the new issue of Us Weekly, their rock star encounter got off to a rather inauspicious start.

Over New Year's, Bieber, 20, hit up a tiny beach bar on the luxe Parrot Cay island in Turks and Caicos, where "there was an old guy throwing back drinks who said, 'Who the f--k are you?'" one source recalls. In response, the "All Around the World" pop star shot back, "I don't know, who the f--k are you?"

Apparently satisfied with that answer, the older gent smiled and said, "'You're a man. I respect that,' then walked away," the source tells Us. It wasn't until a few minutes later, when "another old guy and came over and told Justin, 'Keith Richards wants to have a drink with you,'" that the 71-year-old rock legend's identity was revealed. 

Bieber, rightly awestruck, exclaimed, "Oh, s--t! That was Keith Richards?" and then joined the Brit at a table.

"Justin tried to bro down with him," a witness says, adding that a seemingly unimpressed Richards told the star, "Let's get one thing straight. You're a wannabe."

The first source counters, however, that the two actually had a long talk, after which they "swapped numbers" so they could keep in touch. "Justin called it the best night ever," the insider tells Us.