CHARLOTTE, N.C. — Panthers defensive tackle Louis Leonard has a broken left ankle, another blow to Carolina's thin and shaky defensive line.

Leonard was injured with just over a minute to go on the final defensive play of Sunday's loss at Atlanta. Coach John Fox on Monday wouldn't say for sure that Leonard will be placed on season-ending injured reserve, but the Panthers will almost certainly have to sign another defensive tackle.

Leonard was acquired Sept. 1 from Cleveland for a 2010 late-round draft pick to help replace starter Maake Kemoeatu. Carolina's top run-stuffer was lost to a season-ending ruptured Achilles' tendon on the first day of training camp.

Leonard started alongside Damione Lewis against the Falcons because Nick Hayden was out with a toe injury. Leonard, who played all 16 games with the Browns last season and had four starts, was expected to take hold of the starting job.

"I thought he played pretty well in the game," Fox said. "I think he would have just continued to get better."

The only other defensive tackle on the roster is rookie Ra'Shon Harris, claimed off waivers from Pittsburgh before the season opener. Fox declined to say if he felt Hayden would be available for next Monday's game at Dallas.

"We'll kind of wait and see how his progress goes," Fox said. "Typically we only go into a game with three (activated defensive tackles). We'll kind of evaluate who's available and what our best move will be."

Leonard's injury leaves the Panthers' struggling defense reeling. Carolina has managed two sacks in two games — one by Leonard — and Michael Turner rushed for 105 yards and a touchdown Sunday as Carolina (0-2) remained winless.

Other Panthers injured Sunday included Na'il Diggs (bruised ribs) and fullback Brad Hoover (back spasms). The Panthers won't practice again until Thursday because of the Monday night game.