Reports of a conflict between Jay-Z and Robert DeNiro have fans wondering what exactly went down between the two at Leonadro DiCaprio's birthday party. The bash, held Saturday night at the swanky Darby restaurant in New York City’s West Village, reportedly came complete with an A-list lineup and a heated argument between the two men.

The New York Post reported the dispute started when DeNiro reproached Jay-Z for not returning his calls about a song the rapper was apparently supposed to be working on for the Tribeca Film Festival.

“Bob was sitting at a table, and when Jay-Z went over to say hello, De Niro told Jay that he never called him back,” a source told the Post. “Bob wasn’t in any mood to make polite conversation. He told Jay that if somebody calls you six times, you call them back. It doesn’t matter who you are, that is just rude.”

DeNiro has remained mostly under the gossip radar after a career that’s seen him play some of the most legendary tough guys to ever hit the silver screen. DeNiro, 69, is famous for his roles in “The Godfather Part II,” “Goodfellas,” “Raging Bull” and “Taxi Driver,” among many others.

“De Niro kept telling him that he thinks he’s the man, but that he was disrespectful,’” the Post source continued. “Beyoncé came over, but that didn’t calm Bob down.”

The source added afterward that the incident, “was the talk of the party. Everyone was saying there’s only one star in New York bigger and badder than Jay-Z, and that’s Robert De Niro. He can be quite scary when he’s angry.”

A different source for Page Six, however, said the conversation was “low-key” and far from heated.

While representation for DeNiro and Jay-Z refused to comment on the record, there was quite an audience on hand to witness whatever happened at the Darby, according to The Daily Mail. Chris Rock, Jonah Hill, Edward Norton, Cameron Diaz, Martin Scorsese and new DiCaprio love interest Margot Robbie were all on hand for the festivities, which included a charity tax on every bottle sold.

On the menu was branzino with truffled crust, yellowtail sashimi, spinach truffle pizza appetizer and steak filet with truffles.

Tabloids on both sides of the Atlantic might have been more interested in DiCaprio’s new flame than the heat coming from DeNiro. Robbie, 23, stars alongside DiCaprio in “The Wolf of Wall Street” and was photographed with him at a different party in Las Vegas earlier this month.