Defensive end Grant Irons, a team captain, dislocated his right shoulder and is out for the season.
The injuries came in a disappointing 27-24 overtime loss to top-ranked Nebraska that gave the Irish hope they were ready to compete again with college's elite teams.
Despite the loss, the Irish moved up two spots in the rankings to No. 21.
"We paid a heavy price in that game," Davie said.
The most costly injury was at quarterback, where the Irish have a converted tight end and three freshmen as backups.
"This was unthinkable three hours ago. We all realize what a blow this is. You've all seen how we've evolved as a football team and you've all seen how much work has gone into it, so it's a tremendous blow," Davie said. "It's unthinkable, but it just happened."
Battle, making his second start Saturday, was erratic throwing, going 3-of-15 for 40 yards with one interception. But he rushed for 107 yards. A week earlier in a 24-10 victory over Texas A&M, Battle was 10-of-16 for 133 yards and two touchdowns with no interceptions and rushed for 50 yards.
Battle broke the navicular bone in his non-throwing hand when he was knocked down on the first play of the game. The injury didn't bother him until the second half, Davie said. The coach was told after the game it was just a moderately to slightly sprained wrist.
The wrist was swollen Sunday morning and Battle could not make a fist, so X-rays were taken. It was not immediately known if surgery is required.
"We're going to exhaust all options, have some different people look at it. But right now he is out indefinitely," Davie said.
Irons will undergo surgery after the swelling in his shoulder subsides. Davie said he hopes Irons will return for a fifth season. Davie said Battle also could seek a medical redshirt waiver if he is unable to return.
Coaches hadn't had time to discuss Battle's replacement.
"We're just going to see how it plays out the next day or so and make a decision," Davie said.
The choices are 6-foot-7 Gary Godsey, a sophomore who was recruited to Notre Dame as a tight end, and freshmen Carlyle Holiday, Jared Clark and Matt LoVecchio.
Godsey, the brother of Georgia Tech quarterback George Godsey, is listed as the backup. Davie said Godsey could not run most of the Irish's option plays, although Godsey previously has said he could. Davie described Godsey as "a really good thrower."
Godey, who passed for more than 1,800 yards and 22 touchdowns with four interceptions as a senior at Tampa Jesuit High School, converted from tight end to quarterback last season after Eric Chappell was dismissed from the team.
The Irish have been short-handed at quarterback since C.J. Leak surprised them on signing day 1999 and committed to Wake Forest. Davie had promised Leak that he would not sign another quarterback, so the Irish did not sign any quarterbacks that season. To make up for that, the Irish signed three this year.
Davie said Holiday has a strong arm and is the most athletic of the three freshmen. Clark is the best passer and can run, although he is not an option quarterback, and LoVecchio is a combination of the two.
The problem the Irish coaches face is they have been so busy trying to get Battle ready to play that the others haven't had a lot of chances, Davie said.
The starter at No. 13 Purdue on Saturday may not be the permanent replacement.
"We're going to kind of have maybe a short-range plan because this has caught us by surprise, and then as we evaluate it hopefully come up with a long-range plan," Davie said.
Last season, the Irish sustained some injuries in a disappointing loss to Tennessee and then lost its next three games to finish the season 5-7. Davie said he's not worried about another collapse.
"Why I feel we can be successful is because the character of our other players. There is tremendous character on this team," he said.
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