Serena Williams addresses reporters after here semi-final loss to Kim Clijsters Courtesy PhotoThe U.S. Open said Sunday the Grand Slam Committee Administrator has opened an investigation to determine whether Williams' behavior should be considered a "major offense," which can lead to additional penalties.
Williams also is being docked $500 for racket abuse in what became a 6-4, 7-5 loss Saturday night.
Williams earned $350,000 in prize money for reaching the singles semifinals. She also is scheduled to play in the women's doubles final Monday with her sister Venus.


