Brown 'Broke Rules of Probation' With Nightclub Visit

Chris Brown could live to regret his celebratory night out in Los Angeles hours after he was sentenced for beating up ex-girlfriend Rihanna -- he broke the rules of his probation as he was too young to be in a club.

However, Brown shocked fans by showing little remorse over the vicious attack by heading for a night out on the town at West Hollywood hotspot Guys and Dolls.

Now he is facing a possible investigation into his actions -- as, at 20 years old, he is too young to enter nightclubs and bars in America, according to strict drinking age limits.

The venue he frequented had a Type 48 liquor license, meaning it is only a bar or club and not a restaurant.

Los Angeles Probation Department spokeswoman Kari Webb tells E! News, "It (breaking probation) won't be taken lightly. If you break the law, you're in trouble."

Despite Brown sticking to water throughout the evening, his entourage ordered 10 bottles of champagne, and he would have only been allowed to stay in the club if he was hired as a performer.