Lenoir (knee) was a full participant at the 49ers' practice Thursday, Nick Wagoner of ESPN.com reports.
Lenoir appears to be on track to return to the field Sunday versus the Bears after missing the team's Week 13 loss to the Bills with a knee injury. The 25-year-old will likely be back in his starting role at slot cornerback as the 49ers have entered into must-win territory against Chicago.