SOUTH BEND, Ind. (AP) -- Notre Dame coach Brian Kelly expects some teeth-gnashing while watching the Fighting Irish defense this fall.

The 17th-ranked Irish already were expected to be young on defense in the season opener against Rice on Saturday. That's before learning they'd be without four players, three of them on defense, who are under investigation by the university to determine whether they received improper assistance from others on papers and homework.

Kelly confirmed Tuesday that cornerback KeiVarae Russell, leading returning receiver DaVaris Daniels, defensive end Ishaq Williams and backup linebacker Kendall Moore will not play Saturday, saying he hasn't received any update into the investigation announced publicly by the university on Aug. 15.

When it comes to an academic process involving the honor code, it's out of his hands, Kelly said. That was the case when quarterback Everett Golson was suspended from the university last fall for academic impropriety.

"It does me no good to put a timetable on it. It does me no good to think about what day. I've moved on and the process will take care of itself," he said.

The four remained on the roster handed out Tuesday but were not included on a depth chart that had six freshmen and six sophomores on the two-deep on defense.

Andrew Trumbetti could become the first true freshman to start a season-opener on the defensive line for Notre Dame since Anthony Weaver in 1998, although Trumbetti officially was listed as the backup Tuesday.

"There's a guy that's going to be on the edge of our defense that's going to play a lot of football for us. We're going to have to count on him to play very well for us," Kelly said.

Kelly also listed defensive linemen Jhonny Williams and Grant Blankenship and linebackers Nyles Morgan and Greer Martini as players the Irish will rely on.

"So there are five freshmen right there that are going to have to play some form of winning football for us immediately for us to have the kind of success that we want defensively," Kelly said.

The Irish have ranked in the top 50 in total defense four straight years under Kelly, but are switching to a more aggressive style under new defensive coordinator Brian VanGorder after Bob Diaco left to become head coach at Connecticut.

VanGorder paused last week when asked what it would take for Notre Dame to have a successful defense. He answered that he thinks the Irish have a "developmental defense."

"Maybe the best answer to that is, let's keep getting better as we go through the year. We have a lot of work to do. The players know it. But let's keep improving. Let's keep working. I don't know where we are right now. The one thing I do know is there's a lot better football in front of us," he said.

Kelly said although the Irish are young, he believes they have gifted athletes. Asked Tuesday what could be done to help the defense, Kelly quickly responded: "Score a lot of points. That will ease everybody's concern."

NOTES: Corey Robinson is listed as the starter despite having surgery Friday to put a pin in a fractured thumb. Kelly said he was at practice Monday catching passes. ... Kelly said he hasn't made a decision yet on captains. ... Kelly said the team will sing the alma mater after all home games this season. Some fans were upset last season when the Irish didn't stay on the field for the song after losing to Oklahoma.