Ravens receiver Steve Smith Sr. tweaked his knee at practice Thursday. Mark J. Rebilas Mark J. Rebilas-USA TODAY Sports

Ravens receiver Steve Smith Sr. popped up on Thursday's injury report with an apparent knee injury.

Smith, who was listed as a limited participant, appeared to tweak his knee while running individual drills, according to Jamison Hensley of ESPN.com. The Ravens' top receiver has been dealing with four microfractures in his back, which caused him to miss Week 5's loss to Cleveland.

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The 36-year-old Smith has 41 catches for 588 yards and three touchdowns this season.