Green Bay Packers running back Alex Green has not passed his concussion test and will not play Sunday against the Tennessee Titans.
Ryan Grant, who signed with the injury-plagued Packers earlier this month, will start Sunday for the first time this season.
Green did not practice this week after suffering the concussion in last Sunday's victory over the Chicago Bears. The 24-year-old Green has rushed for a team-leading 464 yards this season.
Grant, who rejoined the Packers on Dec. 5 following a brief stint with the Washington Redskins, rushed for 32 yards on eight carries last week against the Bears.
ESPN senior NFL analyst Chris Mortensen contributed to this report.