Carroll, who could not be reached for comment, still appears to be the leading candidate for the Trojans' vacant coaching job.
But with each hour that passes in this tumultuous search--now entering its 19th day--there remains the possibility for another startling turn of events.
Might San Diego Charger Coach Mike Riley come back into play? And what of the other known candidate, Colorado State's Sonny Lubick?
While Carroll is meeting with USC, the others said they are on hold.
"I don't know anything," Riley told the Associated Press. "I haven't heard anything, don't know anything, haven't talked to anybody at all for a long time."
Lubick also said he had not heard from USC.
Speaking before USC's basketball game against Pepperdine at the Sports Arena, Athletic Director Mike Garrett declined to comment on negotiations with Carroll but reiterated his desire to conduct the search patiently and thoroughly.
Garrett originally interviewed Carroll last week, at which time the former New York Jet and New England Patriot coach was thought to be a longshot.
But then USC's efforts to woo Riley hit several snags--the Charger coach remains under contract and has had second thoughts about uprooting his family.
So Carroll was summoned back to Southern California for a second round of meetings that began Thursday.
As word spread of his return, some fans reacted angrily at the idea of his becoming the new USC coach.
There has been concern that Carroll, 49, has a 34-33 record in the NFL and was fired after three seasons with the Patriots. He has not been involved in the college game since 1983, begging a comparison to fired coach Paul Hackett, who also came to USC from professional football.
Carroll received support Thursday from former Trojan defensive back Ronnie Lott.
"You're going to have concerns about anybody who takes the 'SC job," Lott said of the negative reaction to Carroll. "People expect a lot out of the new coach."
Lott, who finished his career with the Jets, said Carroll contacted him earlier this week to ask about USC.
"He was wanting to make sure he had a feel for the school," Lott said. "He wanted to know what I recalled about it, what made it special."
They talked about recruiting, assistants that Carroll might hire and pressure from alumni and fans. Lott praised his former coach's passion and ability to relate to athletes.
"I told him he has to create that special feeling again," Lott said. "I told him, 'You can't remember the titans, you have to rebuild the titans.' "