Orlando Bloom is alleged to have tried to punch Justin Bieber in a row over his ex-wife Miranda Kerr.
The incident took place outside a restaurant in Ibiza in the early hours of this morning.
Moments after the bust-up, Bieber posted a photograph of Kerr in a bikini to his Instagram page. He has since deleted the image.
Celebrity website TMZ said Bloom tried to throw the punch when 20-year-old Bieber asked Bloom: “What’s up b****?”
A source on the scene told MailOnline: “Justin was being cordial, and everything was fine. But then Orlando was annoyed when he saw it was Justin and instigated by taking a swing at Justin.'
“Justin ducked, and Orlando's punch missed.”
When Bieber scuttled away the crowd is said to have applauded the English actor.
It is unknown why the pair clashed, but the troubled pop star has been linked to Bloom's model ex-wife, Kerr - the mother of his three-year-old son Flynn who he split from last October - in the past. The pair were spotted partying together after a Victoria's Secret fashion show in 2012.
To add yet more fuel to the fire, in April 2014 Bloom enjoyed a meal out with Bieber's on-off girlfriend Selena Gomez.
The restaurant where the alleged incident took place was packed with celebrities at the time, including Paris Hilton, Lindsay Lohan and P Diddy.
