CHARLOTTE, N.C. -- Carolina Panthers running back Jonathan Stewart will miss at least the first six weeks of the season while he recovers from an ankle injury.
Coach Ron Rivera said after practice Tuesday that Stewart was placed on the physically unable to perform list.
The team also put guard Edmund Kugbila, its fourth-round draft pick, on injured reserve with a knee injury and waived injured defensive tackle Frank Kearse and wide receiver Joe Adams, Carolina's fourth-round pick in 2012. Adams and Kearse will go back on injured reserve if they clear waivers.
NFL rules stipulate Stewart can't practice or play for six weeks.
Since the Panthers have a bye in week four, Stewart is eligible to play Oct. 20 against the St. Louis Rams, which would be Week 7 on the NFL calendar but would be Carolina's sixth game of the season.
"I'm just taking it day by day and trying to be there for my teammates and bring as much positive energy as I can," Stewart said. "We have a long season ahead of us and I plan to be back in week six."
Rivera is "very optimistic" Stewart could make it back for St. Louis game.
"Some real good things have happened but they aren't going to happen soon enough," Rivera said, adding doctors now believe the right ankle will take longer to heal. Rivera classified the injury as a sprain. Stewart hasn't practiced since off-season surgery on both ankles.
The decision likely means more playing time for DeAngelo Williams, the franchise's all-time leading rusher, and opens a roster spot for young running backs in Tauren Poole and Armond Smith. Carolina also drafted Kenjon Barner from Oregon in the sixth round and he's expected to contribute as a scat back.
Stewart is coming off a disappointing season a year ago, rushing for 336 yards and one touchdown, both career lows. He missed seven games in all, including the final five with a sprained ankle.
"I can spend all of my energy being disappointed or I can spend all of my energy getting ready for week six," Stewart said.
Stewart said the decision came after he met Tuesday with Dr. James Anderson, the team's physician.
Now the Panthers are awaiting word on fullback Mike Tolbert, who has yet to play in the preseason because of a hamstring injury. His status for the season opener against Seattle remains in question.
Rivera said despite the injuries to Stewart and Tolbert the team has no plans to bring in any running backs.
"We feel good about young guys that we have," Rivera said. "They'll see a dose of action in this last preseason game and we'll see what they're capable of."
The Panthers drafted Kugbila with the 108th overall pick, but he's rarely practiced because of knee and hamstring issues. But Rivera isn't writing him off as a draft-day bust.
"We really have to look at the long term in terms of getting him ready to go in the future," Rivera said.