Arizona Cardinals free agent running back Rashard Mendenhall has decided to retire from the NFL when he leaves his current club, according to his agent.

Mendenhall was expected to enter the free agency, which opens on Tuesday, but instead Mike McCartney wrote on Twitter that the 26-year-old would end his career.

The running back was the Cardinals' most impressive player in the position last season with 687 yards on 217 carries, but has reportedly told coach Bruce Arians that he wants to become an author.

Mendenhall spent five years with the Pittsburgh Steelers before joining the Cardinals last season.