Director Guy Ritchie was forced to call security on the set of his new movie Sherlock Holmes when a crazed fan of his estranged wife Madonna reportedly threatened to stab him to death.

The filmmaker and the singer announced plans to divorce last month, and Ritchie has become a target for obsessed Madonna fans since.

Police were called to his London pub The Punchbowl on Thursday night after a man verbally abused the star, and now it's emerged that cops had to arrest a 16-year-old boy, reportedly wielding a knife, on the set of the Sherlock Holmes remake.

According to Britain's Sunday Mirror newspaper, the unnamed teenager burst onto the set in Manchester, England, waving a 12-inch blade and yelled, "Where's Guy? I'm going to kill him!"

As security guards wrestled the boy to the ground, he allegedly shouted, "I'm Madonna's biggest fan! I'm gonna kill Guy!"

A source tells the publication, "The bloke was screaming about Guy and shouting, 'I love Madonna'. It was terrifying. At first it seemed like a sick joke but it was soon obvious the knifeman was not messing around. Luckily there were four security guards and two policemen who were able to overpower him. Guy was understandably upset, but carried on as if nothing had happened."

A spokesperson for Ritchie was unable to be reached for comment as WENN went to press.

(This news article provided by World Entertainment News Network)