Clayton, who is scheduled for season-ending surgery on his right knee to repair a torn patellar tendon, was hurt early in Sunday's 44-6 loss to the Detroit Lions. He is the third Rams wide receiver to suffer a season-ending injury in 2010. Donnie Avery and Dominique Curry both suffered torn anterior cruciate ligaments.
Later Tuesday, the Rams promoted wide receiver Danario Alexander from the practice squad. Alexander was a star at the University of Missouri last season, but he wasn't drafted after undergoing a fourth operation on his left knee in February. When the Rams signed him in August, Alexander said he was still rehabilitating the knee.
Week 10 has meaning because being on a roster for at least six weeks virtually assures Jackson of an accrued season -- and unrestricted free agency or a franchise-type tag. That season gives him six in the NFL, and in any new CBA, players would need no more than that to earn unrestricted free agency.
Jackson's current tender is around $600,000. He is seeking a long-term deal from the Chargers and an annual salary in the $8 million range.
In order for Jackson to be on the roster for six weeks, however, he must report before Week 8 (Oct. 31). That is because Jackson faces a three-game stint on the roster-exempt list whenever he does report, during which time he will not earn time toward an accrued season. He would be eligible to play and earn credit toward an accrued season beginning Week 12 at Indianapolis.
The Associated Press contributed to this report.