NEW YORK — NFL commissioner Roger Goodell has followed up his suspension of a Tampa Bay cornerback by re-emphasizing safety issues and warning that even first-time offenders will be subject to discipline.

He sent a memo Wednesday night, a day after the league announced the one-game suspension of Tampa Bay cornerback Elbert Mack for a helmet-to-helmet hit on Atlanta quarterback Matt Ryan last week. Mack, an undrafted rookie from Troy, had been fined $5,000 for unnecessary roughness against Houston quarterback Alex Brink during the Bucs' exhibition finale Aug. 28.

"From this point forward, you should be clear on the following point: Any conduct that unnecessarily risks the safety of other players has no role in the game of football and will be disciplined at increased levels, including on a first offense," Goodell wrote in a memo obtained today by The Associated Press. ... "Playing by the rules shows respect for your fellow players. No one wants to see unnecessary injuries."

Goodell ordered that the memo be read and distributed to all players on all 32 teams.

Mack, who plays in nickel and dime defenses and on special teams, will miss Sunday's game with Chicago.

Goodell's letter was a follow-up to the one sent to Mack by Ray Anderson, the league's executive vice president for football operations.

"Your actions are of particular concern in light of the emphasis that our office has placed on developing and enforcing rules designed to protect players from injury, including concussions," Anderson wrote. "The safety of our players is paramount to all of us in the NFL."