Mathieu is dealing with injuries to his calf, heel and groin, Katherine Terrell of ESPN.com reports.
Mathieu left midway through the fourth quarter of Sunday's 26-24 loss to the Falcons due to a groin injury. The 2013 third-round pick told reporters after the game that he had a calf injury earlier in the season and entered Sunday's contest with a lingering heel injury. The Saints will have an extra day's rest heading into their next game against the Chiefs on Oct. 7, and given the myriad of lower-body injuries, Mathieu could be limited or held out of practices leading up to that contest. Through the first four games of the regular season, he's registered 17 tackles (16 solo) and one interception.