The players' union has approved a rule change that will allow one designated player to return from injured reserve and play this season.
The NFL Players Association also agreed to move the league's trading deadline back two weeks to after games in Week 8.
NFL owners voted for both changes in May. But the union had to sign off on them and did so Thursday, six days before the regular season kicks off.
One "marquee'' player placed on injured reserve will be able to return to practice after the sixth week of the schedule and to the lineup after the eighth week. That player must be on the 53-man roster after the final preseason cut, which comes Friday.
Several teams already have candidates for that spot. New York Giants cornerback Terrell Thomas, who missed all of the 2011 season with a right knee injury, aggravated his surgically repaired right anterior cruciate ligament in training camp. He remains on the Giants roster.
Baltimore recently placed Terrell Suggs, last season's Defensive Player of the Year, on the physically unable to perform list, meaning he must sit out at least the first six games. Suggs appeared to fall into the category of the new rule, as well.
Moving the trade deadline could create more action than in the past, when teams rarely moved players at the deadline.