Though it won’t be a certainty until later in the week, all signs from Tuesday’s practice and Pete Carroll’s press conference point to third-year sophomore Mark Sanchez starting at quarterback on Saturday against Arizona. John David Booty threw about 50 passes before practice, and though he was able to grip the ball, his release still bothered him. Even if Booty can play on Saturday, Carroll acknowledged that it might be better to give him a week off to let the finger fully heal. Sanchez, who took all of the snaps with the first team offense Tuesday, overthrew several receivers early in practice, he threw an interception and fumbled a snap, but he seemed to calm down as practice wore on. Sanchez is an excitable player and is known to have a gunslinging mentality in practice, but he acknolwedged to the throng of reporters on Tuesday that he’ll need to play smarter and more conservatively if he’s to take command of the offense Saturday. Carroll expressed his confidence in Sanchez, reminding reporters that even though he hasn’t had a ton of first-team snaps thus far in the fall (likely a key reason he wasn’t used in the second half against Stanford), the staff knows him well. Read on for more injury notes from Tuesday.

• RB Stafon Johnson (bruised foot) thinks he may be able to play Saturday and puts his current condition at 75-85%. He said he wants to be 90% if he plays. Though he did not practice Tuesday, he ran on the sidelines, still not able to get a burst from his toes. Fellow tailback Joe McKnight sat out most of Tuesday’s practice, feeling sick after an energy drink didn’t agree with him.
• LB Thomas Williams (ankle) did not practice Tuesday and showed a noticeable limp. Clay Matthews will start at strong-side linebacker against Arizona if Williams cannot.
• Center Matt Spanos, who required stitches in his lacerated right pinky and ring finger, did not practice Tuesday but assured reporters that he would play Saturday regardless of whether his healing wound “opens or closes, if it’s infected or not. I could care less what it looks like.”
• CB Shareece Wright (Hamstring) appears unlikely to play Saturday accoring to Rivals, but he’ll try to practice Wednesday.
• WR Travon Patterson will undergo season-ending surgery on Friday to repair a bone chip in his right big toe.
• K David Bueller, who had a critical extra point blocked against Stanford, had two field goals blocked in Tuesday’s practice.

USC preparing Sanchez to start against Arizona (LA Daily News)
USC’s Mark Sanchez appears likely to get start (LA Times)
Insider: Sanchez preparation starts at home (Rivals, $)
Bush accuser plans to speak to NCAA (Orange County Register)
Sanchez preparing to lead USC (Orange County Register)
USC Dealing With the Shock (Press-Enterprise)
Pete Carroll-Mike Stoops Discuss Saturday’s Game At The Coliseum (CSTV)