FLOWERY BRANCH, Ga. — The Atlanta Falcons are making new plans at middle linebacker after losing Lofa Tatupu for the season with a chest muscle injury.

The Falcons reported Wednesday for Thursday's first day of training camp with second-year player Akeem Dent suddenly cast as the favorite to replace Curtis Lofton in the middle of the defense. Dent spent most of his rookie season on special teams.

Lofton, who led the team in tackles the last three years, signed with New Orleans.

Tatupu, the former Pro Bowl player with Seattle who did not play last season, was expected to compete with Dent.

"It's hard replacing Tatupu," defensive tackle Peria Jerry said Wednesday. "We wish him the best of luck in getting back to us."

Coach Mike Smith said Tuesday Tatupu will have season-ending surgery after suffering the pectoral injury in a workout.

Another veteran linebacker, 36-year-old Mike Peterson, re-signed with the Falcons on Monday.

"Lofa is a good guy. It definitely was going to be good to play with Lofa," said outside linebacker Stephen Nicholas. "Unfortunately things happen like that. I wish him the best. Football moves on. We signed back Mike Peterson and we're going to put things together. I'm excited."

With Lofton established at middle linebacker, there was little playing time on defense last season for Dent, who was a third-round pick in 2011 from Georgia.

Now Dent will have an opening to open the 2012 season as the starter.

"Akeem is definitely coming along," Nicholas said. "He's catching on to everything fast. He's an ascending player."

Tatupu signed a two-year, $3.6 million contract with Atlanta. He had arthroscopic surgeries on both knees after the 2010 season but said he was physically ready to play last year.

"We were looking forward to Tatupu, but Mike Peterson is a veteran guy and a guy we all look up to in the locker room," Jerry said. "He's a motivator. He gets everybody going."

Tatupu was released before the 2011 season when he wouldn't agree to restructure his contract with the Seahawks.

The Falcons will open camp with Dent, Peterson and three undrafted players, Tennessee State's Rico Council, Pittsburgh's Max Gruder and Pat Schiller of Northern Illinois, at middle linebacker. There may be no position on the team where there is a better opportunity for an undrafted player to emerge in camp and earn significant playing time.

Nicholas, who was held out of minicamp with a toe injury, has been cleared for the start of camp. Nicholas and Sean Weatherspoon are backed up by Robert James and Spencer Atkins at outside linebacker.

New defensive coordinator Mike Nolan is sticking with the team's 4-3 scheme as the base defense. The Falcons' biggest offseason move was their trade for cornerback Asante Samuel, who joins returning starters Brent Grimes and Dunta Robinson at the position.

Notes: DT Corey Peters had a walking boot on his left foot and has not been cleared for the start of camp due to a toe injury. ... Rookie OT Lamar Holmes, a third-round pick from Southern Miss, has been cleared from a foot injury but will be behind after missing the rookie and team mini-camps.