Long (hamstring) has been ruled out for Sunday's game against the Cowboys, Stu Jackson of the Rams' official site reports.
Long was placed on IR with a hamstring injury in early September. The Rams designated him to return this week, and the tight end was able to log three full practice sessions. However, the team isn't yet ready to activate him. Long's next chance to make his regular-season debut with Los Angeles will come Week 9 in Green Bay.