LOS ANGELES — Southern California quarterback Mark Sanchez dislocated his left kneecap and was carted off the practice field today.

Sanchez, the projected starter, was injured after making a throw during practice and landing awkwardly. He was taken for X-rays and an MRI, and team doctors say there is no ligament, cartilage or bone damage. He is listed as day-to-day.

Sanchez said he hopes to be back in time for the Trojans' opener Aug. 30 at Virginia.

"It was scary, frightening at first," Sanchez said. "The way they say these things happen, it could be a lot worse. ... I have heard about people who come back from this in a short period of time and others in a long period. I'm hoping mine is short."

USC's other scholarship quarterbacks are sophomore Mitch Mustain and redshirt freshman Aaron Corp. Mustain redshirted last season after transferring from Arkansas, where he won eight games as a true freshman.

Sanchez started three games last season for an injured John David Booty and won two of them.