Long, who played the first month of the season with a sprained MCL in his knee, has not ruled out playing Thursday night against the Chicago Bears. He may be fitted with a shoulder harness, but he is questionable, at best, the sources said.
Long played with the injury until late in the fourth quarter of the Dolphins' 29-17 victory over the Tennessee Titans.
Dolphins coach Tony Sparano did not disclose many details about Long's injury but added that the former No. 1 pick was a "tough guy."
Long's injury is just the latest ailment for a banged-up Dolphins team that has alternated wins and losses since a two-game losing streak in Weeks 3-4.
Quarterback Chad Pennington was placed on injured reserve Monday with a shoulder injury and fellow signal caller Chad Henne suffered a knee injury against the Titans that may sideline him against the Bears.
The Dolphins listed 13 players -- not including Pennington -- on their injury report Monday, with Henne, Long, Clemons and center Joe Berger (knee) the most seriously hurt.
"We have a lot of guys bumped up right now," Sparano said. "We're sorting through it all."
Chris Mortensen is ESPN's Senior NFL Analyst. Information from The Associated Press contributed to this report.