Bieber made a comment about Orlando's ex-wife Miranda Kerr (saying "What's up, b****?" before adding: "She was good"). Bieber is thought to have gone on a date with her while she was still with the Pirates Of The Caribbean actor.
The Sun reports Moss took him to one side, told him to calm things down and have some more respect. Good job, Kate, good job.
A source told the newspaper: "Kate had a huge go at him and told him he needed to behave. She was giving Bieber some choice words like a teacher after the singer asked to be introduced.
"He'd gone up to say hi to her like his usual cocky self expecting her to gush over him. It was quite a slap in the face."
Kate Moss bringing Justin down a peg or two? Brilliant.
Bieber has fast become the most unpopular guy in Hollywood following the punch up, and as for Miranda? She's keeping a low profile.
LOVE KATE'S STUNNING STYLE? She's still got it, hands down. Take a look through this style file to see more looks from the iconic supermodel.