The alleged victims took lessons from Philippoussis as he works as a personal tennis coach in Northern San Diego County.
The news broke as San Diego Sheriff Bill Gore took to Twitter to share that detectives from the department’s Child Abuse Unit are looking for more victims in the case.
He was arrested at his residence in Mira Mesa, a neighbourhood in San Diego, on Tuesday.
His famous son has yet to comment on the situation.
Nikolaos is a grandfather to Mark's one son who was named after the newly arrested man.