Freshman tailback Dillon Baxter did not travel with the Trojans to play in Saturday's game against Oregon State and is being held out indefinitely pending a compliance inquiry.
Athletic Director Pat Haden said Friday night that Baxter had accepted a ride in a golf cart on campus Thursday and that one of the people on the cart was a student who is a registered sports agent.
"We're on NCAA probation and that means we have to play it as conservatively as we can," Haden said.
Haden said that NCAA rules define the cart ride as an extra benefit. But he said that after an NCAA review and determination of the value of the ride, he hoped to have Baxter's eligibility restored by next week.
In a video posted on USC's website earlier Friday, Coach Lane Kiffin announced why Baxter was being held out and said that Baxter was not aware that one of the students on the cart might have been an agent.
Baxter could not be reached for comment.
On Thursday, Baxter had appeared groggy when he arrived late to practice and did not participate. Kiffin told reporters afterward that Baxter had been hospitalized for part of the day because of an unspecified illness. A school official confirmed that Baxter had been hospitalized Thursday.
The illness and the situation involving the NCAA are the latest setbacks for Baxter, who starred at San Diego Mission Bay High.
Shortly after the NCAA handed down sanctions against USC last summer, a school compliance official sent a letter to the Pacific 10 Conference alleging that Florida, Alabama, Washington, Oregon and Fresno State had improperly contacted Baxter. The schools denied the allegations, and former Athletic Director Mike Garrett later sent letters of apology to their athletic directors.
ESPN.com later reported that a letter of apology from Baxter also was sent, explaining that he had talked with friends at Florida, Michigan, Alabama and Fresno State on the day the sanctions were announced, but was not contacted by other schools.
During training camp, Kiffin suspended Baxter for the season opener against Hawaii for a series of violations of team rules.
Baxter played in the next five games but suffered a toe injury against Stanford that sidelined him for one game and slowed him in another.
He started for the first time on Nov. 6 against Arizona State and probably would have been Marc Tyler's primary backup against Oregon State.
Baxter has rushed for 248 yards and a touchdown and has also caught 11 passes for 73 yards.