Valentino, who has led the Dons to the NCAA playoffs in all three of his seasons, was injured working out prior to the start of official practice and underwent surgery Saturday on his left knee. He is expected to have a complete recovery.
"It is a big blow losing a player of Rob's stature," said USF coach Erik Visser. "He is very versatile and one of the best defenders in the country. He is also a great team leader, who can carry a team on his back."
Valentino helped USF record a 0.88 goals against average in 2006 and also recorded a team-best six assists. He was named to the all-West Coast Conference first team for the third straight season.