BRADENTON, Fla. (AP) - The Panthers have listed running back Jonathan Stewart as questionable for Sunday's season opener at Tampa Bay.

Stewart has been nursing an ankle injury since Carolina's third preseason game against the New York Jets and has not practiced fully since the injury last month.

Despite the numerous options the Panthers have in the backfield to replace Stewart in his absence, coach Ron Rivera feels optimistic about Stewart's chances on playing.

"We do feel pretty good about Jonathan after hearing the progress I was told today," Rivera said after the team's practice at IMG Academy in Bradenton, where the team has been practice since the Democratic National Convention is in Charlotte. "There are reasons for optimism, but we'll probably wait till Sunday morning to make the call. But we like his progress, that's why we're optimistic."

Stewart came off the bench last season and rushed for 761 yards and four touchdowns for the Panthers, earning a five-year contract extension in training camp.

Regardless, DeAngelo Williams will start at running back as usual for the Panthers.

Stewart is often used as to spell Williams and in third down situations. Despite playing in a reserve role, Stewart wound up with more touches than Williams last year because he was so valuable as a receiver.

"When you have a lateral sprain, as he does, the biggest thing you worry about is if he can cut," Rivera said. "He's been doing that very nicely and he's been planting that leg, so he looked pretty good. However, with the rotation of backs we have to use back there, we're confident to go if he's not ready Sunday."

The Panthers have the option to rely more heavily on Williams, who had 836 yards and seven touchdowns in 2011, and newcomer Mike Tolbert, who had 490 yards and eight touchdowns for the Chargers last season. Although Tolbert is listed as a fullback, he's more than capable of carrying the load.

Carolina is also likely to utilize reigning AP Offensive Rookie of the Year Cam Newton, who hurt the Buccaneers on the ground last season, including a 49-yard touchdown run. Newton threw for four TDs and ran for four more last season as Carolina twice routed their division rival.

Williams has also had great success against Tampa Bay in the past, racking up three separate 100-plus-yard performances, including 186-yard performance against the Buccaneers in 2008.