LAKE FOREST, Ill. -- Chicago Bears safety Chris Harris tweaked his injured hamstring at practice Wednesday, delaying his return to the starting lineup, according to a source familiar with the situation.

Harris participated fully in Wednesday's workout before suffering the setback that caused the club to hold him out of Thursday's practice session. He is unlikely to play Sunday against the Carolina Panthers.

Harris underwent treatment Friday in downtown Chicago, but there's a chance the latest setback could be significant enough to keep him out for another game or two, according to the source. He is officially listed as questionable on the injury report.

"I was definitely looking forward to playing these guys," said Harris, who played three seasons in Carolina. "I've still got a bunch of friends on that team. I still keep in contact with a lot of those guys. I still live in Charlotte, so, yeah, it's disappointing not being able to play. But we've got the guys who can go out there and get the job done, and they will get the job done on Sunday."

If Harris can't play Sunday, it's expected that new acquisition Brandon Meriweather would start at free safety, with Major Wright manning the strong safety spot.

"It impacts [us] a lot," Meriweather said. "Chris knows the defense better than anybody in the safety position. He knows it like the back of his hand. Anytime you've got somebody like that with the leadership and the go-get-them personality that Chris has, anytime you lose somebody like that it's huge."

Harris initially strained the hamstring in the second half of the Week 1 win over the Atlanta Falcons, and it was diagnosed as minor at the time.

He practiced at a limited capacity in preparation for the team's outing last week against the Green Bay Packers, but was placed on the game-day inactive list.

"Hamstrings are tricky," Harris said. "It's one of the trickiest injuries to deal with is a hamstring because it's a muscle that you definitely use every single play, and you can't really ... It's kind of hard to gauge where you're at as far as rehab is concerned, as far as your health is concerned."

Bears coach Lovie Smith characterized Harris' setback on Wednesday as soreness before keeping him out the following day.

Harris indicated a desire to play earlier in the week, but the hamstring issue -- which often lingers for players -- is expected to keep him out against the Panthers. Despite Harris' desire to return, he'll have to weigh the potential consequences of trying to come back too early because of the risk of further injury, which could put him on the shelf indefinitely.

Bears linebacker Lance Briggs said Thursday that Harris is "a guy who helps us go," calling the safety a "playmaker and a guy we need on the field."

In Harris' absence, the Bears have given up 57 points in the past two weeks, 567 yards through the air and six touchdowns, with Saints quarterback Drew Brees and Packers quarterback Aaron Rodgers finishing with passer ratings of 118.1 and 111.4, while completing at least 70.3 percent of their passes.

A seventh-year veteran playing in the last year of his contract, Harris contributed five tackles in the opener.

Michael C. Wright covers the Bears for ESPNChicago.com and ESPN 1000. ESPNChicago.com's Jeff Dickerson contributed to this report.