The website claims that the altercation took place just after 9 a.m. and "was intense." Bieber's neighbor allegedly came onto the singer's property to complain that people had been hosting loud parties in Bieber's house while Justin was away on tour, slowly losing his mind.
The L.A. County Sheriff's department confirmed that the neighbor told police Bieber made physical contact with him, and also threatened him.
TMZ's "sources" say that Justin merely told the man to leave his property, and that his security team escorted the man away.
UPDATE: TMZ now says that other "neighborhood sources" are claiming the argument took place because Bieber was racing his new Ferrari around the block this morning. (The original neighbor allegedly went over to confront him about the noise of the car, and the questionable safety of zooming a Ferrari down residential streets.)