And the off-season hits on the Steelers keep on coming.
While it's unclear right now what exactly triggered his alleged violation, Holmes was arrested for marijuana possession in 2008, and the policy states that three failed tests or missed tests results in an automatic four-game suspension.
ESPN reported Saturday morning that QB Ben Roethlisberger is not expected to face charges for sexual assault, but Holmes' latest situation keeps the negative spotlight shining brightly on the organization.
This latest allegation is not connected with a civil suit Holmes is facing in Florida, in which he's accused of throwing a glass in the face of a lady at a night club in Orlando in March. The accuser initially declined to press charges, but the latest report now is she intends to do so.
If the substance abuse allegation and subsequent suspension are true, it further bleakens the horizon for the promising young receiver, who was named the MVP of Super Bowl XLIII after Pittsburgh defeated Arizona 27-23.
Holmes is in the last year of his first contract in the NFL, but will still remain a restricted free agent after the 2010 season under the current collective bargaining agreement.
With the draft coming up, Pittsburgh has conducted visits with five wide receivers: Notre Dame's Golden Tate, Oklahoma State's Dez Bryant, South Florida's Carlton Mitchell, Illinois' Arrelious Benn, SMU's Emmanuel Sanders. If Holmes is suspended for four games, the Steelers would be looking at a trio of Hines Ward, Mike Wallace and veteran Antwaan Randle-El to compliment Roethlisberger and TE Heath Miller.