Coach Tom O'Brien has been telling his players that N.C. State's injury problems have to end sometime.

“Maybe they're going to stop believing me,” he said grimly Monday after announcing two more crippling Wolfpack injuries.

Starting quarterback Russell Wilson and leading tackler Nate Irving both are out for Saturday's game against 13th-ranked South Florida.

Irving injured his right lower leg during last week's 30-24 overtime defeat of East Carolina and missed most of the second half.

O'Brien refused to divulge Wilson's injury or the length of time either player is expected to miss. The coach said both players are out indefinitely.

Asked if Wilson was out because of after-effects from the concussion he suffered Aug. 28 at South Carolina, O'Brien wouldn't comment.

On Mondays, the only requirement for coaches under the new ACC injury policy O'Brien endorsed is to reveal which players have had surgery or are out for the season.

“I don't have to discuss the injury until Thursday,” O'Brien said. “So I'm not going to say anything.”

Wilson returned from a Grade 3 concussion (the most serious) to start at quarterback 16 days later at Clemson. A redshirt freshman, Wilson had the best game of his career against East Carolina, completing 21 of 31 passes for 210 yards and three touchdowns.

During interviews after the game, Wilson appeared fine. As he walked into the Murphy Center football complex on Monday afternoon, there was nothing obviously wrong with him.

(N.C. State does not allow players to speak with reporters on Mondays).

Junior Harrison Beck will replace Wilson as the starter. Senior Daniel Evans, who will back up Wilson, is the only other quarterback on the roster.

Beck started four games last season and came off the bench to pass for 246 yards and spark N.C. State in a win over William & Mary on Sept. 6.

Dwayne Maddox, a freshman who participated in spring practice, will replace Irving at weak side linebacker. Irving has been N.C. State's best player throughout the season, posting team highs of 34 tackles, including 6 tackles for loss, and three interceptions.

O'Brien said Maddox did some nice things in Irving's place in the second half, but also made mistakes that N.C. State needs to correct.

“Nate Irving means a great deal to the team,” said starting middle linebacker Ray Michel. “He's an experienced player. I wouldn't say it's going to be hard to replace him, but it's going to be a little drought without him there.”

In terms of personnel, N.C. State already was parched before Monday.

Top wide receiver Donald Bowens (lower back stress fractures), running back Toney Baker (knee), backup tight end Matt Kushner (knee) and safety Javon Walker (knee) are gone for the season because of injuries.

Defensive tackle Alan-Michael Cash (knee), tight end Anthony Hill (strained chest muscle) and safety Clem Johnson (broken jaw) are out indefinitely.

Running back Jamelle Eugene missed three games with an ankle injury before returning against East Carolina.

“You've got nine or 10 starters that aren't playing on this football team,” O'Brien said, “and it's consistently been this way. When you look at the schedule we've played, it's amazing that we've played the way we have.”

Ken Tysiac: 919-829-8942