Philippoussis Sr, 68, a tennis coach, looked frail and confused when he was led into Vista's Superior Court, north of San Diego, in handcuffs, leg irons and a blue prison jumpsuit on Thursday.
The incidents happened in Fairbanks Ranch, Philippoussis' home, and his auto said prosecutors.
According to the San Diego County Sheriff's Department's inmate tracking website, Philippoussis had been booked on suspicion of sexual intercourse or sodomy with a child 10 years old or younger, lewd and lascivious acts on a child under 14 and oral copulation of a person under 18.
"Probably a parent's worst nightmare having someone in a position of trust a teacher, a coach, a student, an instructor, then to violate that trust repeatedly over this type of conduct over this period of time, yeah it's serious", Garrett Wong, Deputy District Attorney, said.
Mr Tegnelia, however, said his client was innocent and would fight the charges.
Bail has been set for Nikolaos Salvator Philippoussis at 9.2 million dollars.
"He's looking forward to diligently defending his case", Tegnelia said. Mark attended the arraignment Thursday.
Mr Tegnelia said Mark Philippoussis has offered to provide any comfort for his father during his jail stay.
When Mark first learned of the charges, Tegnelia said, he was shocked.
Philippoussis, an Australian citizen, was ordered to surrender his passport if he does post bail, but his lawyer told the San Diego Union-Tribune that was impossible. Our investigation is ongoing from today. Sheriff's investigators say there are no indications that other children were molested but it's a possibility they're considering.