Justin Bieber is being investigated for battery against a neighbor in Calabasas, Calif. after allegedly getting into a scuffle.

What was the guy so mad about? The fact that Bieber apparently isn't just a maniac on the floor, but also in the Ferrari.

Bieber returned to his mansion after a hellish time overseas on his Believe tour, and he had a new vehicular toy waiting for him on a flatbed truck late Monday night (March 25) -- which he promptly raced down the street early the next morning, going an estimated 100mph.

TMZ reports that Bieber's neighbor, who actually races cars for fun himself, confronted the singer for his dangerous drag-racing. Apparently not only was it super hazardous -- there are a lot of kids in the neighborhood, many of whom were home for spring break -- but also almost as loud as the screams he elicits from arenas.

Justin and his neighbor reportedly got into a shouting match, which may or may not have escalated into a physical altercation, depending on who you ask.

While it's unclear exactly what went down during the incident, Bieber's neighbor is citing the Canadian expat for battery, claiming some sort of physical contact occurred between the two guys, who are both 5'7" and a waifish and delicate 135 pounds.

Other neighbors corroborate the story of the alleged victim, who admits to being hot under the collar when he confronted Bieber about his behavior.

However, sources close to Bieber disagree, claiming that Justin told the neighbor to get off his property and that a yelling match did happen -- but that no physical contact was made.

Bieber hasn't had the best luck with his cars lately, but at least this time the issues were his own.

You're rich, bro. Get a driver and keep the pricey rides in your garage.