GREEN BAY - Clay Matthews is expected to miss at least a month with a broken thumb, according to reports by ESPN's Adam Schefter and the website profootballtalk.com.
Matthews fractured his thumb during a sack of Matthew Stafford in Sunday's win over the Lions.
Packers coach Mike McCarthy says he doesn't know how long Matthews will be out, but McCarthy is "hopeful" it's not a season ending injury.
Matthews also missed the second half of Green Bay's loss to Cincinnati with a hamstring injury.
The team put Robert Francois on injured reserve Monday.