The Panthers took a two-fisted hit along their defensive line Tuesday when rookie defensive tackles Sione Fua and Terrell McClain were placed on injured reserve.

The loss of the two starters for the remainder of the season forced the Panthers to shuffle their personnel again. It likely means second-year tackle Andre Neblett and rookie Frank Kearse will fill their roles.

The Panthers also signed free-agent defensive tackle Ogemdi Nwagbuo and Jason Shirley from the practice squad. Nwagbuo played three seasons under Ron Rivera with the San Diego Chargers, and Shirley spent one week with Seattle this season after being released by Cincinnati during training camp.

The hit comes at the same position where free agent Ron Edwards, expected to anchor the defensive interior, was lost for the season to a torn triceps during training camp.

Fua suffered a hamstring injury while going through pregame warmups Sunday at Tampa Bay. He didn't play against the Bucs and had an MRI on Monday. He had nine tackles this season.

McClain aggravated a sprained MCL, and the decision was made to sit him down for the remaining four games this season. McClain had 19 tackles and one sack.

The Panthers got a glimpse at their new defensive front against Tampa Bay, and it was effective, limiting running back LeGerrette Blount to just 19 rushing yards in 11 carries. The front is sure to get a test this Sunday when the Falcons and running back Michael Turner visit Bank of America Stadium.

Coach Ron Rivera praised the play of Neblett and Kearse after they were forced into major roles against the Bucs. He also said the Panthers are fortunate that defensive ends Charles Johnson, Greg Hardy and Antwan Applewhite are able to shift inside when the situation demands it.

"Charles and Greg move inside as well as any in the league," defensive coordinator Sean McDermott said.

The loss of Fua and McClain comes as the Panthers are coming off their second-best defensive effort of the season, limiting Tampa Bay to 285 yards. Only Jacksonville, with 257 yards during a rainstorm, had fewer yards against the Panthers.

"They're coming together," Rivera said of the defense. "They're understanding our run fits. It's one thing we'll continue to get better at. They're understanding where guys are going to be.

"When you watch (the Tampa Bay) tape like we did, you see for the first time as a unit our defensive line really held the point of attack. It helped our linebackers flow to their creases and, at the same time, it helped our linebackers get downhill which really helped our defensive line.

"Any time you get those groups coming together, that helps tremendously in the run game. If you force people to throw the ball, it helps you. Now you can put your ears back and go. We saw that (against Tampa Bay) in the way Charles played, the way Greg Hardy played. Those guys were doing the things you need to have done to win a game. We need to continue that."