CHARLOTTE, N.C. -- Carolina Panthers running back DeAngelo Williams did not practice on Friday for the second straight day with a thigh injury and is listed as questionable for Sunday's home opener against the Detroit Lions.

Williams did run prior to practice, but his status for the game is up in the air.

"I'm concerned,'' coach Ron Rivera said. "He's a running back and he's got to rely on that burst. Based on what he ran today, I've got to see where he is tomorrow. If he's the slightest big hampered by it, [he'll sit].''

Williams, 31, led Carolina (1-0) with 72 yards rushing in last week's 20-14 victory over Tampa Bay. He practiced full on Wednesday, then came in with a sore thigh on Thursday.

"It's the burst you always worry about,'' Rivera said.

Williams led the team in rushing with 843 yards last season and is the team's all-time leader with 6,627 rushing yards and 46 rushing touchdowns.

He has dedicated this season to his mother, who died of breast cancer in May. He died his hair pink for the opener at Tampa Bay.

If Williams doesn't play, Jonathan Stewart will get the start. Stewart has missed most of the last two seasons with ankle injuries, but said prior to this season he felt the best he has in three years.

Stewart has 4,036 career rushing yards. He had a career-best 1,133 yards in 2009 when he and Williams became the first pair of backs to rush for more than 1,100 yards on the same team in the same season.

Rivera said Stewart would split carries with Mike Tolbert and Fozzy Whittaker if Williams can't play. Whittaker led the team in rushing during the preseason.

Meanwhile, tight end Greg Olsen returned to practice after leaving on Thursday to be with his son T.J., who is recovering from his third open heart surgery since being born in 2012 with a congenital heart defect.

Rivera didn't go into details but said things were going well for Olsen's son.