Notre Dame will have to rebound from one of its worst defensive performances of the season without one of its cornerstones.
Irish coach Brian Kelly said nose guard Ian Williams will miss four to six weeks with an MCL injury. Reports of the senior's injuries first surfaced Monday night.
Kelly said Williams sprained his MCL, and that the injury will not require surgery.
"It seems to be the worst-kept secret in America," Kelly said Tuesday of Williams' injury. "We will be able to modify any of those comments based upon when we can get him moving around again.
"It's an injury that some come back quicker than others. We will be able to get a better feel for it next week."
Williams suffered the injury in Saturday's 35-17 to Navy, in which Notre Dame gave up a season-high 367 rushing yards.
Kelly said he is hopeful receiver Michael Floyd, who didn't play against Navy because of a hamstring injury, and linebacker Carlo Calabrese, who suffered a hamstring injury Saturday, will be able to play this weekend against Tulsa.
Floyd is expected to practice this week after not participating in preparation for Navy last week.
Receiver Theo Riddick will be put back into a cast as he tries to heal from a sprained ankle, and he will miss at least three to four more weeks, Kelly said.
Safety Jamoris Slaughter remains in a backup role this week as he continues to battle a heel injury.
"It's been a slow healing process for him," Kelly said of Slaughter. "We think he made some progress this past week. He felt better today. Hopefully, we will get more out of him."
Kelly said receiver TJ Jones, who moved into the slot receiver spot with Riddick out, is fine and was suffering more from fatigue than anything else.
Notre Dame will turn to Sean Cwynar to start at nose guard for Williams, who has 37 tackles. Cwynar will be backed up by Hafis Williams, who will slide over from a defensive end spot.
"We feel good about Sean stepping in at that position," Kelly said. "The next player for us is Hafis, and Sean can't play the whole game. Hafis and Sean together can get that done."
Freshman Kona Schwenke, who hasn't played this year, will be a backup defensive end with Hafis Williams moving inside. Emeka Nwankwo is the other backup end.
"We want take a good look at Kona," Kelly said. "Kona will be that next defensive end in, whether it is for Ethan (Johnson) or (Kapron Lewis-Moore)."