Green Bay Packers linebacker Clay Matthews has been ruled out for a month with a thumb injury, according to a report.

Matthews sustained the injury during the third quarter of his side's 22-9 victory over the Detroit Lions on Sunday, breaking his thumb when he sacked Lions quarterback Matthew Stafford.

The four-time Pro Bowler underwent surgery on the injury and is now expected to miss one month, according to ESPN.

It is bad news for the Packers, who lost two other linebackers to injuries against the Lions, but it is better than they feared, with coach Mike McCarthy expressing concern yesterday that it could be a season-ending injury.

Matthews is likely to miss matches against the Baltimore Ravens, Cleveland Browns, Minnesota Vikings and Chicago Bears as the Packers look to improve upon their 2-2 start to the NFL season.