PITTSBURGH - Thomas Smith was expected to anchor Pittsburgh's inexperienced defensive line from his tackle spot, but now there's a chance he might not play in the opening game.

A fifth-year senior, Smith was hobbled by a twisted knee and will undergo arthroscopic surgery Friday to mend the damage. Smith will miss the remaining training camp practices at the UPMC Sports Complex, and his status for the opener with Notre Dame is up in the air.

But first-year Pitt coach Dave Wannstedt said the goal is to get Smith healthy by that game.

"The thoughts from the doctors right now are that he will be back," Wannstedt said. "Everybody thought that because of the type of cleanup that they're going to do in there that it was an attainable goal."

Smith, who was a starting defensive end last season, is amiable off the field. However, the 6-foot-4, 300-pounder is a monster in the middle of Pitt's defense and will be difficult to replace if he doesn't return in time for the game against the Fighting Irish at 8 p.m. Sept. 3 at Heinz Field.

"We have a lot of good players up front," Smith said before his injury. "I know that I don't have to make every play. We have a lot of speed on defense, and we're going to be very tough to run on this season."

The Panthers have been pushed around up front in recent years and several big running backs have shredded their defense for more than 200 yards on the ground. Pitt has some beef in the middle this year, along with some quickness there and on the outside as well, to stop that trend.

Senior Phil Tillman (6-1, 315) moves into Smith's spot for now, while redshirt freshman Corey Davis (6-1) from Peabody in the Pittsburgh City League is the other tackle. Freshman Rashaad Duncan (6-1, 280), redshirt freshman Nick Williams (6-2, 275) and fifth-year senior Ron Idoko (6-2, 300) are battling for backup spots.

"No matter who the starters are, we're going to rotate all four guys in there," Wannstedt said. "I think you guys know how I like to play defensive linemen, so we'll play eight guys (on the line) every week. ... We've got plenty of guys to mix it up in there."

Notes:

Also on the injury front, wideout Greg Lee (right shoulder) has continued to improve. He has missed eight days now, but wore a helmet for the first time Thursday and worked in all the drills except those with contact. ... Outside linebacker Brian Bennett (left knee) missed Wednesday night's workout and Thursday's, but his injury isn't believed to be serious. ... Pitt's second intrasquad scrimmage is Friday afternoon.