MELBOURNE, Australia (AP) - A former tennis coach of Mark Philippoussis and Monica Seles was found guilty Monday of sexually abusing a female student at a Melbourne school 20 years ago. A Victorian County Court jury found former teacher Gavin Maxwell Hopper, 48, of Hope Island, Queensland, guilty of three counts of indecent assault and six of gross indecency. The victim, now aged 33, told the court she had a three-year sexual relationship with Hopper from January 1985, when she was 14. Hopper pleaded not guilty to the charges and denied the relationship took place. He worked as a mathematics and physical education teacher at Melbourne's Wesley College. He coached Seles in 1998, Philippoussis from 1999 to early 2000 and Germany's Tommy Haas later in 2000. Hopper, who was held in custody following the verdict while he awaits sentencing, now runs a Gold Coast tennis academy with former Wimbledon champion Pat Cash of Australia. Hopper's lawyers said he will appeal the decision.