Already down one player, No. 22 Notre Dame (8-3) could have to face No. 4 Stanford (10-1) on Saturday without two more significant contributors.
Receiver Theo Riddick and defensive end Stephon Tuitt may not be available this weekend.
Riddick has missed the last two games because of a hamstring injury, and coach Brian Kelly said he would have a better idea whether the junior can play after Tuesday's practice.
"He felt like this week he should be able to contribute," Kelly said of Riddick during his Tuesday news conference. "We'll run him around again today and give him an opportunity to really assess where he is after today's practice.
"Generally, if there's not a lot of soreness and we see that burst, we figure him into what we do on Saturday. Today is an important day for him."
Tuitt missed last Saturday's 16-14 win over Boston College because of illness, and Kelly said they are monitoring the freshman to see whether he can play at the end of the week.
"He's still ill," said Kelly, who would not elaborate on what kept Tuitt out of the BC game. "He's still not feeling well."
Kelly also confirmed that senior running back Jonas Gray suffered a torn anterior cruciate ligament in his right knee in last weekend's win over Boston College. Gray, who ran for 791 yards and 12 touchdowns, also suffered other damage in his knee and will have surgery soon, Kelly said.
Notre Dame will turn to freshman George Atkinson III and Cam McDaniel to back up starting running back Cierre Wood. Riddick, who played running back in his first season at Notre Dame, could also be an option if he is able to play this weekend.
"They have to play a significant role, both of them," Kelly said of the freshmen running backs. "Theo offers us some versatility if we think it is necessary."