And coach Bo Pelini's defense can't stop the run.
The Cornhuskers haven't started the hardest part of their schedule, and their fan base is antsy after last week's 34-23 loss at double-digit underdog Minnesota.
"Trust me, I'm not making any excuses," Pelini said Monday. "It's my job, and our job, to get it right. That's why the first thing I say is I'm responsible for it. But I know this, if I panic or we panic ... you have to stay the course."
The Huskers (5-2, 2-1 Big Ten) host Northwestern (4-4, 0-4) on Saturday needing a win to stay in the thick of the Legends Division race.
The week didn't start well for quarterback Taylor Martinez. Already playing with a sore left (non-throwing) shoulder and nagging toe injury, he came out of the Minnesota game with a hip pointer and couldn't practice Sunday.
Pelini said Martinez is day to day. If the Huskers had to play Monday, he said, Tommy Armstrong Jr. would have been the starter.
Martinez's left foot injury initially was described as turf toe, but Martinez said after the Minnesota game it was something else. Pelini said Monday that Martinez's second and third toes are sprained.
While Martinez sat out the previous three games, Pelini had told reporters he wouldn't play Martinez against Minnesota unless he was 100 percent.
After the game, Martinez admitted to reporters he wasn't at full strength.
"We communicated during the week and I looked him in the eye and I said, 'Taylor, can you perform everything we ask you to perform up to the level we expect you to perform it? It's OK to say no.'
"I don't know how he's feeling. But if he looks me in the eye and says, "Yes, I'm ready to go,' I felt we had to give him the opportunity to get back out there and play."
Pelini said from his view on the sideline, he didn't think Martinez struggled. "It didn't look like a guy who was gimping around."
The Huskers also struggled with dropped passes and with pass protection, giving up a season-high four sacks. They were playing for the first time without their best lineman, guard Spencer Long.
Pelini said he'll tweak his defensive personnel against Northwestern in an effort to shore up the run defense. David Santos, who has been playing middle linebacker, will move to his more natural weakside spot. Michael Rose and Josh Banderas will take over in the middle.
"I'm not putting this on David Santos by any means, but it's not his strength," Pelini said. "You don't want to take a square peg and pound it into a round hole."
The Huskers are looking for answers for a rush defense that allows 173.7 yards a game to rank 77th nationally. Nebraska has allowed 44 runs of more than 10 yards, and opponents are rushing for an average of 5.3 yards on first down — both Big Ten-worst marks.
Nebraska allowed a season-high 271 yards rushing to the Gophers.
"Believe me, we don't like the feeling of losing to a team we felt we should have handled," Rose said.
"We didn't like the feeling of being talked about as a defense that's terrible and not good enough to win ball games. We take those things to heart and we're going to do our best to make sure that's not a problem again."
Four of the five remaining regular-season opponents are strong running teams. Northwestern averages 182 yards on the ground, but will be without injured back Venric Mark, who has been battling leg injuries.
"I do believe in these kids and what they're going to be," Pelini said. "I want to fast forward to when we're hitting on all cylinders."