Par for N.C. State's 2011 football season, the team's off week did not go according to plan.

The anticipated return of several key defensive players on the injured list didn't materialize, and running back Mustafa Greene was ruled out for the season.

The Wolfpack (3-3) has to win four of its next six games to return to a bowl game, starting with Saturday's trip to Virginia. State will have to do that with the players on hand, coach Tom O'Brien said Monday.

"Time always helps, but I think the way we're set up right now, is probably how we're going to play the rest of the year," O'Brien said. "This is who and what we are. We have to find a way to make this work."

O'Brien officially shut Greene down for the season Monday. The team's leading rusher a year ago had missed the first six games with a foot injury. O'Brien said Greene needed a second surgery next week, which made any attempt at a comeback this season futile. Instead, Greene will redshirt.

Greene led State with 597 rushing yards in 2010 as a true freshman. He caught 30 passes for 272 yards and scored six total touchdowns.

"He was a really good back last year and he was better in the spring until he went down," O'Brien said.

Greene suffered a foot injury in April during spring practice. N.C. State has not provided details about the injury other than he had offseason surgery. O'Brien said Greene will need a second surgery to remove a plate.

At 6-foot and 200 pounds, Greene added a dimension of size and speed at running back that State's offense has missed this season.

James Washington has posted back-to-back 100-yard games and leads the team with 409 yards and five touchdowns but Curtis Underwood (shoulder) has missed the past two games and O'Brien didn't sound optimistic that either Underwood or fullback Taylor Gentry (ankle) would be able to play Saturday.

Defensive end Jeff Rieskamp (shoulder) and defensive tackle Thomas Teal (foot) are also out for the team's first trip to Charlottesville, Va., since 2006.

Defensive tackle A.J. Ferguson is the one player expected to return for Saturday's game.

Linebacker Terrell Manning and defensive lineman Brian Slay came back for State's 38-24 win over Central Michigan on Oct. 8.

Defensive tackle J.R. Sweezy played in the past two games but was not listed on the depth chart on Monday. O'Brien said Sweezy, the defensive captain, is being "re-evaluated."

Senior linebacker Audie Cole, the team's leading tackler and one of the few constants in the defensive lineup, said it is up to the healthy players to make a run in the second half of the season.

"I don't know who's back and who's not," Cole said. "Whoever is out there, is who we deal with. You can't worry about what's not there."

State used six different starting lineups on defense in the first six games.

The instability, and absence of top players like Sweezy and Rieskamp, contributed to lopsided losses to Cincinnati and Georgia Tech.

State ranks 89th in scoring defense (30.1 points per game) and 88th in total defense (412 yards per game). The defense is eighth nationally with a plus-7 turnover margin, and 19th nationally with 17 sacks in six games, but it has been undone by mistakes, especially on third down.

Bowl Subdivision opponents have converted on 24-of-54 third-down attempts in four games against State's defense.

"That's what we have to fix," Cole said.

And that's a fix they'll have to make without any reinforcements from the injured list.

Giglio: 919-829-8938