SANTA CLARA -- Aldon Smith will return from a five-game hiatus and play Sunday when the 49ers host the Carolina Panthers, defensive coordinator Vic Fangio said Thursday.
"I'm sure he'll play some," Fangio said. "We'll monitor the situation, if nothing between now and then. Nothing's been set in stone."
Smith's conditioning may not be enough for him to resume an every-down role.
"It'll be a fluid situation," Fangio said.
Smith was in substance-abuse treatment between Sept. 23 and Oct. 28, and he rejoined his teammates last week.
Fangio said the 49ers' premier pass-rusher was a "little rusty" but is expected to return to top form "quickly."
Smith has accured 38 sacks since debuting in 2011 as the 49ers' first-round draft pick out of Missouri. He set a franchise record with 19 ½ sacks last season and had 4½ through the first three games this season.
James has been a healthy scratch the past three games, but his speed and play-making ability need to get on the field, coach Jim Harbaugh said last week. Kyle Williams has served as the 49ers' primary return man this season, but he's coming off a shaky performance against the Jacksonville Jaguars.
"When my number's called, I'll be ready," James said. "I've got to take advantage of my opportunity."
James was poised to seize the punt-return role this offseason, but a knee injury in the exhibition finale shelved him for the first three regular-season games.
Oregon's all-time leading rusher, James admittedly struggled in the punt-return capacity in his two exhibition seasons.
"At first it was a little shaky," James said. "I never really did it much in college. I did it one year. ... I was just kind of free-styling in college."
"It's day-to-day with him and we'll see how it progresses through the week," offensive coordinator Greg Roman said.
Carolina (5-3) at 49ers (6-2), 1:05 p.m. Fox