Schefter also reported there's "some optimism" Mathieu could play in the team's season opener Sept. 8 against the San Diego Chargers.
The second-year pro was placed on the PUP list before training camp as he recovered from tearing his ACL and LCL against the St. Louis Rams last Dec. 8.
Mathieu is ahead of schedule in his rehab. In June, Cardinals coach Bruce Arians said he was looking for Mathieu to return by Oct. 1; on Aug. 7, Mathieu said he was two to three weeks away. But by last Tuesday, Arians said the safety could return within a week, lining up with his reported activation.
A third-round pick by the Cardinals in the 2013 NFL draft, Mathieu started 11 games in his rookie season, finishing with 65 tackles, two interceptions and a sack.
- Ben Estes