No structural damage found in Sanchez's fragile left knee

Doctors found no structural damage to Mark Sanchez's left knee, but coach Pete Carroll called the USC quarterback's status "day-to-day" as the Trojans prepare for a visit from Arizona State.

Sanchez watched Monday's practice from an equipment cart, and said he was hoping to be able to play Saturday. "I'd be upset to be on the sideline but very supportive," Sanchez told the Los Angeles Times. "Hopefully, it doesn't come to that."

Sanchez suffered the bone bruise in his knee in the Trojans' 44-10 victory against Oregon when he was dragged down from behind by Nick Reed. After remaining down for a few moments, Sanchez walked off the field under his own power and later returned for a series.

Carroll told reporters the injury is unrelated to the dislocated left kneecap Sanchez suffered in the preseason. The earlier injury is why Sanchez has been wearing a knee brace.

If the junior can't go, Mitch Mustain is in line to step in, though the Trojans' backup role has changed hands three times in as many weeks.

Mustain, a sophomore who transferred from Arkansas, moved up to No. 2 from No. 4 last week. "I feel like I'm prepared and on top of the game plan," Mustain said, according to the Times.

Ted Miller covers the Pac-10 for ESPN.com.